CN105319442B - The frequency power signal detection method and system modulated according to cosine function - Google Patents
The frequency power signal detection method and system modulated according to cosine function Download PDFInfo
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Abstract
The present invention relates to a kind of frequency power signal detection method and system modulated according to cosine function.The present invention is modulated by cosine function for the larger signal sequence of initial phase excursion, obtains the cosine function modulation sequence of zero initial phase or initial phase near zero.The cosine function modulation sequence avoids the influence of the larger problem of initial phase excursion, cosine function modulation sequence carries the larger signal sequence all phase difference information of numerical value at the same time, can significantly improve the accuracy of frequency power signal calculating, improve anti-harmonic wave and noise jamming.The frequency accuracy for the electric power signal that the present invention obtains can reach 10‑10Magnitude, the accuracy that frequency calculates are higher.
Description
Technical field
The present invention relates to technical field of electric power, is examined more particularly to a kind of frequency power signal modulated according to cosine function
Survey method, the frequency power signal detecting system modulated according to cosine function.
Background technology
The measurement of the sine parameter of electric system includes frequency measurement, phase measurement, amplitude measurement etc..Fourier transformation is
Realize the basic skills of sine parameter measurement, be widely used in electric system.But with sine parameter e measurement technology
Development, Fourier transformation there are the problem of also more aobvious protrusion, it is difficult to further meet electric system to sine parameter high precision
Spend the requirement calculated.
In terms of electric system sine parameter measurement, there are some improved measurement method of parameters, such as zero hands over method, based on filter
The mensuration of ripple, the mensuration based on Wavelet Transform, based on neutral net, based on DFT (Discrete Fourier
Transform, discrete Fourier transform) conversion mensuration etc..The specified power frequency of operation of power networks belongs near 50Hz (hertz)
The relatively low sinusoidal frequency of frequency.Due to the complexity that the limitation and signal of actual signal treatment technology are formed, such as signal discrete
The data quantization ambient noise that sampling produces influences, and signal sequence blocks caused spectrum leakage problem and is objectively difficult to avoid that,
The influence of any initial phase problem of signal, the influence of direct current and subharmonic and subharmonic problem in signal etc., these algorithms
Measurement accuracy it is relatively low, and anti-harmonic wave and noise jamming are poor.
The content of the invention
Based on this, it is necessary to detected in view of the above-mentioned problems, providing a kind of frequency power signal modulated according to cosine function
Method and system, it is possible to increase accuracy, the anti-harmonic wave of raising and the noise jamming that frequency calculates.
In order to solve the above technical problems, the present invention adopts the following technical scheme that：
A kind of frequency power signal detection method modulated according to cosine function, including step：
According to the lower limit of frequency power signal scope, preset sample frequency and default integer signal period number, obtain preliminary
Sample sequence length；
The electric power signal is tentatively sampled according to the preliminary sample sequence length, obtains the electric power signal
Preliminary sample sequence；
To the preliminary sample sequence into line frequency preliminary survey, obtain the preliminary frequency of the electric power signal, according to it is described just
Synchronizing frequency determines reference frequency；
According to the preset sample frequency and the reference frequency, the unit period sequence length of the electric power signal is obtained
Degree；
According to the default integer signal period number and the unit period sequence length, predetermined sequence length is obtained；
According to the predetermined sequence length, positive sequence is obtained from the preliminary sample sequence；
The positive sequence is reversely exported, obtains the anti-pleat sequence of the positive sequence；
The positive sequence is added with the anti-pleat sequence, obtains the cosine function modulation sequence of zero initial phase；
The cosine function modulation sequence is truncated, obtains truncated sequence；
By the cosine function of the reference frequency and the SIN function of the reference frequency respectively with the cosine function tune
Sequence processed is multiplied, and obtains the first real frequency sequence vector and the first empty frequency sequence vector；
By the cosine function of the reference frequency and the SIN function of the reference frequency respectively with the truncated sequence phase
Multiply, obtain the second real frequency sequence vector and the second empty frequency sequence vector；
Digital notch is carried out to the described first real frequency sequence vector and the first empty frequency sequence vector respectively, obtains first
Real frequency vector trap sequence and the first empty vectorial trap sequence of frequency；
Integral operation is carried out to the described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency respectively,
Obtain the first real frequency vector integrated value and the first empty vectorial integrated value of frequency；
Digital notch is carried out to the described second real frequency sequence vector and the second empty frequency sequence vector respectively, obtains second
Real frequency vector trap sequence and the second empty vectorial trap sequence of frequency；
Integral operation is carried out to the described second real vectorial trap sequence of frequency and the second empty vectorial trap sequence of frequency respectively,
Obtain the second real frequency vector integrated value and the second empty vectorial integrated value of frequency；
According to default phase transition rule, the described first empty vectorial integrated value of frequency is integrated with the described first real frequency vector
Value is converted to first phase；The described second empty vectorial integrated value of frequency and the described second real vectorial integrated value of frequency are converted into the second phase
Position；
According to default initial phase transformation rule, the first phase and the second phase are converted into the cosine letter
The initial phase of number modulation sequence；
According to default all phase difference transformation rule, the initial phase of the cosine function modulation sequence is converted to described remaining
The all phase of string FUNCTION MODULATION sequence is poor；
According to default frequency power signal transformation rule, all phase difference of the cosine function modulation sequence is converted to
The frequency of the electric power signal.
A kind of frequency power signal detecting system modulated according to cosine function, including：
Preliminary sample sequence length determination modul, for the lower limit according to frequency power signal scope, preset sample frequency
With default integer signal period number, preliminary sample sequence length is obtained；
Preliminary sample sequence acquisition module, for being carried out just to the electric power signal according to the preliminary sample sequence length
Step sampling, obtains the preliminary sample sequence of the electric power signal；
Reference frequency determining module, for, into line frequency preliminary survey, obtaining the electric power signal to the preliminary sample sequence
Preliminary frequency, reference frequency is determined according to the preliminary frequency；
Unit period sequence length determining module, for according to the preset sample frequency and the reference frequency, obtaining
The unit period sequence length of the electric power signal；
Predetermined sequence length determination modul, for according to the default integer signal period number and the unit period sequence
Length, obtains predetermined sequence length；
Positive retrieval module, for according to the predetermined sequence length, being obtained just from the preliminary sample sequence
To sequence；
Anti- pleat retrieval module, for the positive sequence reversely to be exported, obtains the anti-pleat sequence of the positive sequence
Row；
Cosine function modulation sequence determining module, for the positive sequence to be added with the anti-pleat sequence, obtains zero
The cosine function modulation sequence of initial phase；
Truncated sequence acquisition module, for the cosine function modulation sequence to be truncated, obtains truncated sequence；
Primary vector sequence determining module, for by the sine of the cosine function of the reference frequency and the reference frequency
Function is multiplied with the cosine function modulation sequence respectively, obtains the first real frequency sequence vector and the first empty frequency sequence vector；
Secondary vector sequence determining module, for by the sine of the cosine function of the reference frequency and the reference frequency
Function is multiplied with the truncated sequence respectively, obtains the second real frequency sequence vector and the second empty frequency sequence vector；
First trap sequence determining module, for respectively to the described first real frequency sequence vector and the first empty frequency vector
Sequence carries out digital notch, obtains the first real frequency vector trap sequence and the first empty vectorial trap sequence of frequency；
First integral value determining module, respectively falls into the described first real vectorial trap sequence of frequency and the first empty frequency vector
Wave train carries out integral operation, obtains the first real frequency vector integrated value and the first empty vectorial integrated value of frequency；
Second trap sequence determining module, for respectively to the described second real frequency sequence vector and the second empty frequency vector
Sequence carries out digital notch, obtains the second real frequency vector trap sequence and the second empty vectorial trap sequence of frequency；
Second integral value determining module, for the vectorial trap sequence of frequency real to described second respectively and the second empty frequency to
Measure trap sequence and carry out integral operation, obtain the second real frequency vector integrated value and the second empty vectorial integrated value of frequency；
Phase determination module, for regular according to default phase transition, by the described first empty frequency vector integrated value and institute
State the first real vectorial integrated value of frequency and be converted to first phase；By the described second empty vectorial integrated value of frequency and the described second real frequency vector
Integrated value is converted to second phase；
Initial phase determining module, for according to default initial phase transformation rule, by the first phase and described second
Phase transition is the initial phase of the cosine function modulation sequence；
All phase difference determining module, for according to default all phase difference transformation rule, the cosine function to be modulated sequence
The all phase that the initial phase of row is converted to the cosine function modulation sequence is poor；
Frequency detection module, for according to default frequency power signal transformation rule, the cosine function to be modulated sequence
The all phase difference of row is converted to the frequency of the electric power signal.
The frequency power signal detection method and system that the present invention is modulated according to cosine function, for initial phase excursion
Larger signal sequence, is modulated by cosine function, obtains the cosine function modulation sequence of zero initial phase or initial phase near zero
Row.The cosine function modulation sequence avoids the influence of the larger problem of initial phase excursion, while cosine function modulation sequence
Row carry the larger signal sequence all phase difference information of numerical value, can significantly improve frequency power signal calculating accuracy,
Improve anti-harmonic wave and noise jamming.The frequency accuracy for the electric power signal that the present invention obtains can reach 10-10Magnitude, frequency
The accuracy of calculating is higher.
Brief description of the drawings
Fig. 1 is the flow diagram for the frequency power signal detection method embodiment that the present invention is modulated according to cosine function；
Fig. 2 is the schematic diagram of the positive sequence of the present invention and anti-pleat sequence length；
Fig. 3 is the experimental result schematic diagram that the frequency power signal obtained using the method for the present invention detects relative error；
Fig. 4 is the structure diagram for the frequency power signal detecting system embodiment that the present invention is modulated according to cosine function；
Fig. 5 is the structure diagram of phase determination module embodiment of the present invention.
Embodiment
In order to which the technical solution for being better understood from the technical problem to be solved in the present invention, taking and the technology reached are imitated
Fruit, is below in conjunction with the accompanying drawings described in detail the embodiment of the present invention.
As shown in Figure 1, a kind of frequency power signal detection method modulated according to cosine function, including step：
S101, according to the lower limit of frequency power signal scope, preset sample frequency and default integer signal period number, obtain
Preliminary sample sequence length；
S102, according to the preliminary sample sequence length tentatively sample the electric power signal, obtains the electric power
The preliminary sample sequence of signal；
S103, to the preliminary sample sequence into line frequency preliminary survey, the preliminary frequency of the electric power signal is obtained, according to institute
State preliminary frequency and determine reference frequency；
S104, according to the preset sample frequency and the reference frequency, obtain the unit period sequence of the electric power signal
Row length；
S105, according to the default integer signal period number and the unit period sequence length, obtain predetermined sequence length
Degree；
S106, according to the predetermined sequence length, obtain positive sequence from the preliminary sample sequence；
S107, reversely export the positive sequence, obtains the anti-pleat sequence of the positive sequence；
The positive sequence, be added by S108 with the anti-pleat sequence, obtains the cosine function modulation sequence of zero initial phase；
S109, truncated the cosine function modulation sequence, obtains truncated sequence；
S110, by the cosine function of the reference frequency and the SIN function of the reference frequency respectively with the cosine letter
Number modulation sequence is multiplied, and obtains the first real frequency sequence vector and the first empty frequency sequence vector；
S111, by the cosine function of the reference frequency and the SIN function of the reference frequency respectively with the truncation sequence
Row are multiplied, and obtain the second real frequency sequence vector and the second empty frequency sequence vector；
S112, carry out digital notch to the described first real frequency sequence vector and the first empty frequency sequence vector respectively, obtains
To the first real frequency vector trap sequence and the first empty vectorial trap sequence of frequency；
S113, respectively integrate the described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency
Computing, obtains the first real frequency vector integrated value and the first empty vectorial integrated value of frequency；
S114, carry out digital notch to the described second real frequency sequence vector and the second empty frequency sequence vector respectively, obtains
To the second real frequency vector trap sequence and the second empty vectorial trap sequence of frequency；
S115, respectively integrate the described second real vectorial trap sequence of frequency and the second empty vectorial trap sequence of frequency
Computing, obtains the second real frequency vector integrated value and the second empty vectorial integrated value of frequency；
S116, according to default phase transition rule, will the described first empty vectorial integrated value of frequency with described first it is real frequently to
Amount integrated value is converted to first phase；The described second empty vectorial integrated value of frequency and the described second real vectorial integrated value of frequency are converted to
Second phase；
S117, according to default initial phase transformation rule, the first phase and the second phase are converted to described
The initial phase of cosine function modulation sequence；
S118, according to default all phase difference transformation rule, the initial phase of the cosine function modulation sequence is converted to
The all phase of the cosine function modulation sequence is poor；
S119, according to default frequency power signal transformation rule, all phase of the cosine function modulation sequence is poor
Be converted to the frequency of the electric power signal.
Electric power signal is the sinusoidal signal based on a kind of fundamental wave component.Sinusoidal signal extensively criticizes string function signal and cosine letter
Number signal.Frequency power signal scope is generally 45Hz~55Hz.So lower limit f of frequency power signal scopeminIt can be taken as
45Hz.Default integer signal period number C2πIt can be configured according to actual needs, for example, being set to 11 etc..In one embodiment
In, preliminary sample sequence length N can be determined according to formula (1)start：
Wherein, (int) represents rounding；fnFor preset sample frequency, unit Hz；NstartUnit dimensionless, C2πList
Position dimensionless, fminUnit be Hz.
After obtaining preliminary sample sequence length, electric power signal is tentatively sampled according to preliminary sample sequence length.Example
Such as, the electric power signal is single fundamental frequency cosine function signal, according to preliminary sample sequence length to single fundamental frequency cosine
Function signal is tentatively sampled, the preliminary sample sequence X of the electric power signal of acquisitionstart(n) it is formula (2)：
Wherein, A is signal amplitude, and unit can be v；ω is signal frequency, unit rad/s；TnFor sampling interval, list
Position is s；fnFor preset sample frequency, unit Hz；N is series of discrete number, unit dimensionless；For signal initial phase, unit is
rad；NstartFor preliminary sample sequence length, unit dimensionless.
After obtaining preliminary sample sequence, method, the algorithm based on filtering can be handed over, based on Wavelet Transformation Algorithm, base by zero
Algorithm in neutral net, the frequency algorithm based on DFT transform or frequency algorithm based on phase difference etc. are to preliminary sample sequence
Into line frequency preliminary survey, preliminary frequency ω is obtainedo, preliminary frequency ωoUnit be rad/s.In one embodiment, can should
Preliminary frequency is used as and refers to frequency, i.e. reference frequency ωs=ωo.Reference frequency ωsUnit is rad/s.
After obtaining reference frequency, in one embodiment, unit period sequence length N can be determined according to formula (3)2π：
Wherein, (int) is round numbers；fnFor preset sample frequency, unit Hz；fsFor the reference frequency of Hz units, ωs
For the reference frequency of rad/s units；N2πUnit dimensionless.There are in 1 sampling interval for unit period sequence length integer
Error.
After obtaining unit period sequence length, in one embodiment, predetermined sequence length N is determined according to formula (4)：
N=(int) (C2πN2π) (4)
Wherein, (int) is round numbers；The unit dimensionless of N.From formula (4) as can be seen that predetermined sequence length N and integer
Signal period number C2πIt is corresponding.Predetermined sequence length N can the periodic sequence length N in units of2π11 times.Since there are error, institute
It is about to state the signal period integer that predetermined sequence length is included.
After obtaining default series length N, according to predetermined sequence length, positive sequence is obtained from the preliminary sample sequence
Row.In one embodiment, the preliminary sample sequence obtained based on formula (2), the positive sequence X that the present invention obtainsi(n) it is formula
(5)：
Wherein, Xstart(n) it is preliminary sample sequence；A is signal amplitude, and unit can be v；ω is signal frequency, unit
For rad/s；TnFor sampling interval, unit s；N is series of discrete number, unit dimensionless；For signal initial phase, unit is
rad；N is positive sequence length, that is to say predetermined sequence length, unit dimensionless.
The positive sequence obtained based on formula (5), anti-pleat sequence X of the invention-i(- n) is formula (6)：
Wherein, β is anti-pleat sequence initial phase, and anti-pleat sequence initial phase is the cut-off phase of positive sequence, i.e., described electric power
The cut-off phase of signal, unit rad；N is anti-pleat sequence length, as shown in Fig. 2, anti-pleat sequence length and positive sequence length
It is identical, unit dimensionless.
The anti-pleat sequence that positive sequence and formula (6) based on formula (5) obtain, the cosine letter for zero initial phase that the present invention obtains
Number modulation sequence Xcos(n) it is formula (7)：
Wherein, AcosFor the amplitude of cosine function modulation sequence, unit v；For at the beginning of cosine function modulation sequence
Phase, unit rad；N is the series of discrete value of dimensionless unit；N is the cosine function modulation sequence length of dimensionless unit,
Cosine function modulation sequence length is identical with positive sequence length.Allow positive sequence initial phaseWith anti-pleat sequence initial phase β
Excursion in 0~± 0.375 π rad.
It is reference frequency error since predetermined sequence length corresponds to default integer signal period number there are one of error, reason
Caused error, the two of reason is the integer error of predetermined sequence length.If the error is zero, cosine function tune
Sequence initial phase processedIt is zero, on the contrary cosine function modulation sequence initial phaseNear zero.The first phase
PositionError compared with null value and be proportional relation between the error of the default integer signal period number.
After obtaining cosine function modulation sequence, the cosine function modulation sequence is truncated, as shown in formula (8), is obtained
Truncated sequence is obtained, wherein, truncated length can be the unit period sequence length N2π0.25 times：
Wherein, Xs(n) it is truncated sequence；N is the cosine function modulation sequence length of dimensionless unit, that is to say default sequence
Row length；NsFor the truncated sequence length of dimensionless unit；MsFor the shortening value of opposite cosine function modulation sequence length, unit
Dimensionless；N2πFor the unit period sequence length of dimensionless unit.
When without considering mixing interfering frequency component, obtained the first real frequency sequence vector R1(n) and the first empty frequency is vectorial
Sequence I1(n) it is formula (9)：
When without considering mixing interfering frequency component, obtained the second real frequency sequence vector R2(n) and the second empty frequency is vectorial
Sequence I2(n) it is formula (10)：
Mixing interfering frequency is included in real frequency sequence vector and empty frequency sequence vector.When in input signal include direct current into
Point, subharmonic component and during subharmonic component, the mixing interfering frequency will be more complicated, these mixing interfering frequencies will be tight
Ghost image rings the accuracy that frequency calculates.Although window function and integral operation have good decay to mixing interfering frequency in itself
Effect, but there is no specific aim, it is impossible to the inhibitory action of depth is produced to complicated mixing interfering frequency, it is impossible to meet sinusoidal ginseng
Several high accuracies, which calculates, to be needed.
In order to targetedly suppress to be mixed the influence of interfering frequency, the present invention uses a kind of digital trap.Preferable feelings
Under condition, the null Frequency point of digital trap just corresponds to the mixing interfering frequency point, to the mixing interfering frequency tool
There is complete inhibitory action.In one embodiment, digital notch specifically uses digital averaging filtering algorithm, i.e., connects several
Continuous centrifugal pump is added, and then takes its arithmetic mean of instantaneous value to be exported as this filter value.Digital notch needs to set digital notch to join
Number, the digital notch parameter refer to the length N that several continuous centrifugal pumps are addedD.In digital notch parameter NDValue is unit week
At 1.5 times of phase sequence length, the mixing interfering frequency that can be produced to 1/3 subharmonic suppress.And NDValue is single
At 2 times of bit period sequence length, can to direct current, 1/2 by several times, 1 time, 2 times, 3 times, 4 times, the mixing of the generation such as 5 subharmonic
Interfering frequency is suppressed.Therefore, digital notch is made of the digital trap of 2 kinds of parameters, it is contemplated that physical presence error
Deng factor, influenced in order to which depth suppresses mixing interfering frequency, the digital trap of every kind of parameter is by three identical series of parameter
Word trap forms, and totally six grades of arithmetic mean of instantaneous value digital notch are formed.In one embodiment, six grades of arithmetic mean of instantaneous value numerals are fallen into
Waves can be formula (11)：
Wherein, X (n) is digital notch list entries, sequence length N；XD(n) it is digital notch output sequence, sequence length
Spend N-3ND1-3ND2；ND1For notch parameter 1, i.e., continuous centrifugal pump is added quantity；ND2For notch parameter 2, i.e. continuous centrifugal pump phase
Addend amount.
In one embodiment, notch parameter ND1Value is 1.5 times of the unit period sequence length of the reference frequency,
Notch parameter ND2Value is 2 times of the unit period sequence length of the reference frequency, and six grades of arithmetic mean of instantaneous value digital notch need
To use 10.5 times of unit period sequence lengths.
Under the premise of the mixing interfering frequency component is completely suppressed, the described first real frequency vector trap sequence and institute
It is (12) to state the first empty vectorial trap sequence of frequency：
Wherein, RD1(n) it is the first real vectorial trap sequence of frequency；ID1(n) it is the first empty vectorial trap sequence of frequency；K (Ω) is
Dimensionless gain of the digital notch in frequency difference Ω；α (Ω) is rad unit phase shift of the digital filtering in frequency difference Ω；ND1Join for trap
Number 1；ND2For notch parameter 2.
Equally, under the premise of mixing interfering frequency component is completely suppressed, the vectorial trap sequence of the second real frequency and
The described second empty vectorial trap sequence of frequency is formula (13)：
Wherein, RD2(n) it is the described second real vectorial trap sequence of frequency；ID2(n) it is the described second empty vectorial trap sequence of frequency
Row；K (Ω) is dimensionless gain of the digital filtering in frequency difference Ω；α (Ω) is phase shift of the digital filtering in frequency difference Ω, and unit is
rad；ND1For notch parameter 1；ND2For notch parameter 2.
In one embodiment, the present invention carries out integral operation using existing integrator in the prior art.Using integration
Device carries out integral operation to the described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency, and it is real to obtain first
The vectorial integrated value of frequency and the first empty vectorial integrated value of frequency are formula (14)：
Wherein, R1For the first real vectorial integrated value of frequency；I1For the first empty vectorial integrated value of frequency；L1 is integral and calculating length 1,
Unit dimensionless, L1 are 0.5 times of unit period sequence length.
Equally, using integrator respectively to the described second real vectorial trap sequence of frequency and the second empty vectorial trap sequence of frequency
Row carry out integral operation, and it is formula (15) to obtain the second real frequency vector integrated value and the second empty vectorial integrated value of frequency：
Wherein, R2For the second real vectorial integrated value of frequency；I2For the second empty vectorial integrated value of frequency.L2 is integral and calculating length 2,
Unit dimensionless, L2 are 0.25 times of unit period sequence length.
In one embodiment, step S120 can include：
Determine the first ratio of the described first empty vectorial integrated value of frequency and the described first real vectorial integrated value of frequency；
Using the opposite number of the arctan function value of first ratio as the first phase；
Determine the second ratio of the described second empty vectorial integrated value of frequency and the described second real vectorial integrated value of frequency；
Using the opposite number of the arctan function value of second ratio as the second phase.
As shown in formula (16) and formula (17), obtained first phase and second phase are respectively：
Wherein, PH1For first phase, unit rad；R1For the first real vectorial integrated value of frequency；I1For the first empty frequency vector product
Score value；PH2For second phase, unit rad；R2For the second real vectorial integrated value of frequency；I2For the second empty vectorial integrated value of frequency；L1
For the integral and calculating length 1 of the dimensionless unit；L2 is the integral and calculating length 2 of the dimensionless unit.
It should be noted that above-mentioned first ratio, the second ratio, just to distinguish each ratio, reduced value is not suitable
Sequence is limited.
After obtaining first phase and second phase, in one embodiment, cosine function tune can be determined according to formula (18)
The initial phase of sequence processed
The all phase difference of cosine function modulation sequence is signal sinusoidal frequency and cosine function modulation sequence time span
Product.All phase difference Δ PH and initial phaseRelation be：Initial phaseSubstantially represent the predetermined sequence length
The error amount of the corresponding integer signal period number, if error amount is zero, all phase difference is 2 π integral multiples, otherwise institute
State the non-2 π integral multiples of all phase difference, initial phaseOpposite number again just reflects 2πIntegral multiple and non-2πThe mistake of integral multiple
Difference.
In one embodiment, all phase difference Δ PH of cosine function modulation sequence can be determined according to formula (19)：
Wherein, 2 π C2πAll phase for 2 π integral multiples is poor；Work as C2πWhen=11,2 π C2π=22 π, then the scope of Δ PH is in 22 π
Left and right, unit rad.
The relation for being signal sinusoidal frequency with the product of cosine function modulation sequence time span according to all phase difference, can be with
Draw：Frequency power signal is the ratio of all phase difference and cosine function modulation sequence time span.It is so true according to formula (20)
Determine the frequencies omega of electric power signal：
Wherein, ω is the frequency of the electric power signal of rad/s units；TnN is the modulation sequence time span of s units.
In order to be better understood from the technique effect that technical solution of the present invention reaches, carried out with reference to a specific embodiment
Explanation.
Assuming that the experimental signal provided is formula (21)：
For signal fundamental frequency excursion in 45Hz-55Hz, round numbers signal period number is about 11, the change of signal initial phase
The π rad of scope 0~± 0.375, the sample frequency of signal are 10kHz, the discrete data quantization digit 24bit of signal, frequency preliminary survey
Relative error<| ± 0.25% |, obtain frequency power signal detection absolute relative error | Ferr(f) | with signal fundamental frequency f
The experimental result of variation characteristic is as shown in Figure 3.According to Fig. 3 as can be seen that the experimental signal frequency detecting that provides of the present invention is accurate
Degree is 10-10Magnitude, accuracy are higher.
Based on same inventive concept, the present invention also provides a kind of frequency power signal detection system modulated according to cosine function
System, is below in conjunction with the accompanying drawings described in detail embodiments of systems of the invention.
As shown in figure 4, a kind of frequency power signal detecting system modulated according to cosine function, including：
Preliminary sample sequence length determination modul 101, for the lower limit according to frequency power signal scope, default sampling frequency
Rate and default integer signal period number, obtain preliminary sample sequence length；
Preliminary sample sequence acquisition module 102, for according to the preliminary sample sequence length to the electric power signal into
The preliminary sampling of row, obtains the preliminary sample sequence of the electric power signal；
Reference frequency determining module 103, for, into line frequency preliminary survey, obtaining the electric power letter to the preliminary sample sequence
Number preliminary frequency, reference frequency is determined according to the preliminary frequency；
Unit period sequence length determining module 104, for according to the preset sample frequency and the reference frequency, obtaining
To the unit period sequence length of the electric power signal；
Predetermined sequence length determination modul 105, for according to the default integer signal period number and the unit period
Sequence length, obtains predetermined sequence length；
Positive retrieval module 106, for according to the predetermined sequence length, being obtained from the preliminary sample sequence
Positive sequence；
Anti- pleat retrieval module 107, for the positive sequence reversely to be exported, obtains the anti-pleat of the positive sequence
Sequence；
Cosine function modulation sequence determining module 108, for the positive sequence to be added with the anti-pleat sequence, obtains
The cosine function modulation sequence of zero initial phase；
Truncated sequence acquisition module 109, for the cosine function modulation sequence to be truncated, obtains truncated sequence；
Primary vector sequence determining module 110, for by the cosine function of the reference frequency and the reference frequency
SIN function is multiplied with the cosine function modulation sequence respectively, obtains the first real frequency sequence vector and the first empty vectorial sequence of frequency
Row；
Secondary vector sequence determining module 111, for by the cosine function of the reference frequency and the reference frequency
SIN function is multiplied with the truncated sequence respectively, obtains the second real frequency sequence vector and the second empty frequency sequence vector；
First trap sequence determining module 112, for respectively to the described first real frequency sequence vector and the first empty frequency
Sequence vector carries out digital notch, obtains the first real frequency vector trap sequence and the first empty vectorial trap sequence of frequency；
First integral value determining module 113, respectively the vectorial trap sequence of frequency real to described first and the first empty frequency to
Measure trap sequence and carry out integral operation, obtain the first real frequency vector integrated value and the first empty vectorial integrated value of frequency；
Second trap sequence determining module 114, for respectively to the described second real frequency sequence vector and the second empty frequency
Sequence vector carries out digital notch, obtains the second real frequency vector trap sequence and the second empty vectorial trap sequence of frequency；
Second integral value determining module 115, for respectively to the described second real vectorial trap sequence of frequency and second void
The vectorial trap sequence of frequency carries out integral operation, obtains the second real frequently vectorial integrated value and the second empty vectorial integrated value of frequency；
Phase determination module 116, for according to default phase transition rule, will the vectorial integrated value of the described first empty frequency and
The described first real vectorial integrated value of frequency is converted to first phase；By the described second empty vectorial integrated value of frequency and the described second real frequency to
Amount integrated value is converted to second phase；
Initial phase determining module 117, for according to default initial phase transformation rule, by the first phase and described
Two phase is converted to the initial phase of the cosine function modulation sequence；
All phase difference determining module 118, for according to default all phase difference transformation rule, the cosine function to be modulated
The all phase that the initial phase of sequence is converted to the cosine function modulation sequence is poor；
Frequency detection module 119, for according to default frequency power signal transformation rule, the cosine function to be modulated
The all phase difference of sequence is converted to the frequency of the electric power signal.
Electric power signal is the sinusoidal signal based on a kind of fundamental wave component.Sinusoidal signal extensively criticizes string function signal and cosine letter
Number signal.Frequency power signal scope is generally 45Hz~55Hz.So lower limit f of frequency power signal scopeminIt can be taken as
45Hz.Default integer signal period number C2πIt can be configured according to actual needs, for example, can be by the default integer signal period
Number C2πIt is arranged to 11.In one embodiment, the preliminary sample sequence length determination modul 101 can basisDetermine preliminary sample sequence length Nstart, wherein (int) represents rounding, fnFor default sampling frequency
Rate.
After the preliminary sample sequence length determination modul 101 obtains preliminary sample sequence length, preliminary sample sequence obtains
Modulus block 102 tentatively samples electric power signal according to preliminary sample sequence length.For example, the electric power signal is single fundamental wave
Frequency cosine function signal, preliminary sample sequence acquisition module 102 is according to preliminary sample sequence length to single fundamental frequency cosine
Function signal is tentatively sampled, the preliminary sample sequence X of the electric power signal of acquisitionstart(n) it is：Wherein, A is signal amplitude；ω is signal frequency；Between sampling
Every；fnFor preset sample frequency；N=0,1,2,3 ... .., Nstart- 1, it is series of discrete number；For signal initial phase；Nstart
For preliminary sample sequence length.
After preliminary sample sequence acquisition module 102 obtains preliminary sample sequence, reference frequency determining module 103 can pass through
Zero hands over method, the algorithm based on filtering, the algorithm based on Wavelet Transformation Algorithm, based on neutral net, the frequency based on DFT transform to calculate
Method or frequency algorithm based on phase difference etc., into line frequency preliminary survey, obtain preliminary frequency ω to preliminary sample sequenceo.In a reality
Apply in example, reference frequency determining module 103 can be using the preliminary frequency as referring to frequency, i.e. reference frequency ωs=ωo。
After reference frequency determining module 103 obtains reference frequency, in one embodiment, unit period sequence length determines
Module 104 can basisDetermine unit period sequence length N2π.Wherein (int) is round numbers, fnFor
Preset sample frequency,fsFor the reference frequency of Hz units, ωsFor the reference frequency of rad/s units.Unit period
There are the error in 1 sampling interval for sequence length integer.
After unit period sequence length determining module 104 obtains unit period sequence length, in one embodiment, preset
Sequence length determining module 105 is according to N=(int) (C2πN2π) determine predetermined sequence length N.Wherein (int) is round numbers, C2π
For default integer signal period number, N2πFor unit periodic sequence length.Predetermined sequence length N and integer are can be seen that from the formula
Signal period number C2πIt is corresponding.Predetermined sequence length N can the periodic sequence length N in units of2π11 times.Since there are error, institute
It is about to state the signal period integer that predetermined sequence length is included.
After predetermined sequence length determination modul 105 obtains default series length N, positive retrieval module 106 is according to pre-
If sequence length, positive sequence is obtained from the preliminary sample sequence.In one embodiment, based on above-mentioned preliminary sampling sequence
The preliminary sample sequence that row acquisition module 102 obtains, the positive sequence X that positive retrieval module 106 obtainsi(n) it is：Wherein, Xstart(n) it is preliminary sample sequence；A is signal width
Value；ω is signal frequency；TnFor the sampling interval；N=0,1,2,3 ... .., N-1, are series of discrete number；N≤Nstart；For letter
Number initial phase；N is positive sequence length, that is to say predetermined sequence length.
The positive sequence obtained based on above-mentioned positive retrieval module 106, anti-pleat retrieval module 107 obtains anti-
Pleat sequence X-i(- n) is：X-i(- n)=Xi(N-n)=Acos (- ω Tnn+β).Wherein n=0,1,2,3 ... .., N-1；β is anti-
Pleat sequence initial phase, anti-pleat sequence initial phase are the cut-off phases of positive sequence, i.e., the cut-off phase of described electric power signal；N is
Anti- pleat sequence length, as shown in Fig. 2, anti-pleat sequence length is identical with positive sequence length.
What the positive sequence and anti-pleat retrieval module 107 obtained based on above-mentioned positive retrieval module 106 was obtained
Anti- pleat sequence, the cosine function modulation sequence X for zero initial phase that cosine function modulation sequence determining module 108 obtainscos(n) it is：
Wherein, AcosFor the amplitude of cosine function modulation sequence, unit v；For at the beginning of cosine function modulation sequence
Phase, unit rad；N is the series of discrete value of dimensionless unit；N is the cosine function modulation sequence length of dimensionless unit,
Cosine function modulation sequence length is identical with positive sequence length.Allow positive sequence initial phaseWith anti-pleat sequence initial phase β
Excursion in 0~± 0.375 π rad.
It is reference frequency error since predetermined sequence length corresponds to default integer signal period number there are one of error, reason
Caused error, the two of reason is the integer error of predetermined sequence length.If the error is zero, cosine function tune
Sequence initial phase processedIt is zero, on the contrary cosine function modulation sequence initial phaseNear zero.The first phase
PositionError compared with null value and be proportional relation between the error of the default integer signal period number.
After obtaining cosine function modulation sequence, truncated sequence acquisition module 109 carries out the cosine function modulation sequence
Truncate, be shown below, obtain truncated sequence：
Xs(n)=Xcos(n)
Ns=N-Ms
Ms=0.25N2π
Wherein, Xs(n) it is truncated sequence；N is the cosine function modulation sequence length of dimensionless unit, that is to say default sequence
Row length；NsFor the truncated sequence length of dimensionless unit；MsFor the shortening value of opposite cosine function modulation sequence length, unit
Dimensionless；N2πFor the unit period sequence length of dimensionless unit.
When without considering mixing interfering frequency component, the first real frequency that primary vector sequence determining module 110 obtains is vectorial
Sequence R1(n) and the first empty frequency sequence vector I1(n) it is：
When without considering mixing interfering frequency component, the second real frequency that secondary vector sequence determining module 111 obtains is vectorial
Sequence R2(n) and the second empty frequency sequence vector I2(n) it is：
Mixing interfering frequency is included in real frequency sequence vector and empty frequency sequence vector.When in input signal include direct current into
Point, subharmonic component and during subharmonic component, the mixing interfering frequency will be more complicated, these mixing interfering frequencies will be tight
Ghost image rings the accuracy that frequency calculates.Although window function and integral operation have good decay to mixing interfering frequency in itself
Effect, but there is no specific aim, it is impossible to the inhibitory action of depth is produced to complicated mixing interfering frequency, it is impossible to meet sinusoidal ginseng
Several high accuracies, which calculates, to be needed.
In order to targetedly suppress to be mixed the influence of interfering frequency, the present invention uses a kind of digital trap.Preferable feelings
Under condition, the null Frequency point of digital trap just corresponds to the mixing interfering frequency point, to the mixing interfering frequency tool
There is complete inhibitory action.In one embodiment, digital notch specifically uses digital averaging filtering algorithm, i.e., connects several
Continuous centrifugal pump is added, and then takes its arithmetic mean of instantaneous value to be exported as this filter value.Digital notch needs to set digital notch to join
Number, the digital notch parameter refer to the length N that several continuous centrifugal pumps are addedD.In digital notch parameter NDValue is unit week
At 1.5 times of phase sequence length, the mixing interfering frequency that can be produced to 1/3 subharmonic suppress.And NDValue is single
At 2 times of bit period sequence length, can to direct current, 1/2 by several times, 1 time, 2 times, 3 times, 4 times, the mixing of the generation such as 5 subharmonic
Interfering frequency is suppressed.Therefore, digital notch is made of the digital trap of 2 kinds of parameters, it is contemplated that physical presence error
Deng factor, influenced in order to which depth suppresses mixing interfering frequency, the digital trap of every kind of parameter is by three identical series of parameter
Word trap forms, and totally six grades of arithmetic mean of instantaneous value digital notch are formed.In one embodiment, six grades of arithmetic mean of instantaneous value numerals are fallen into
Waves are：
Wherein, X (n) is digital notch list entries, sequence length N；XD(n) it is digital notch output sequence, sequence length
Spend N-3ND1-3ND2；ND1For notch parameter 1, i.e., continuous centrifugal pump is added quantity；ND2For notch parameter 2, i.e. continuous centrifugal pump phase
Addend amount.
In one embodiment, notch parameter ND1Value is 1.5 times of the unit period sequence length of the reference frequency,
Notch parameter ND2Value is 2 times of the unit period sequence length of the reference frequency, and six grades of arithmetic mean of instantaneous value digital notch need
To use 10.5 times of unit period sequence lengths.
Under the premise of the mixing interfering frequency component is completely suppressed, the first trap sequence determining module 112 obtains
The described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency be：
Wherein, RD1(n) it is the first real vectorial trap sequence of frequency；ID1(n) it is the first empty vectorial trap sequence of frequency；K (Ω) is
Dimensionless gain of the digital notch in frequency difference Ω；α (Ω) is rad unit phase shift of the digital filtering in frequency difference Ω；ND1Join for trap
Number 1；ND2For notch parameter 2.
Equally, under the premise of mixing interfering frequency component is completely suppressed, the second trap sequence determining module 114 obtains
The described second real vectorial trap sequence of frequency and the second empty vectorial trap sequence of frequency be：
Wherein, RD2(n) it is the described second real vectorial trap sequence of frequency；ID2(n) it is the described second empty vectorial trap sequence of frequency
Row；K (Ω) is dimensionless gain of the digital filtering in frequency difference Ω；α (Ω) is phase shift of the digital filtering in frequency difference Ω, and unit is
rad；ND1For notch parameter 1；ND2For notch parameter 2.
In one embodiment, the present invention carries out integral operation using existing integrator in the prior art.First integral
Be worth determining module 113 using the vectorial trap sequence of integrator frequency real to described first and the first empty vectorial trap sequence of frequency into
Row integral operation, obtains the first real frequency vector integrated value and the first empty vectorial integrated value of frequency is：
Wherein, R1For the first real vectorial integrated value of frequency；I1For the first empty vectorial integrated value of frequency；L1 is integral and calculating length 1,
Unit dimensionless, L1 are 0.5 times of unit period sequence length.
Equally, second integral value determining module 115 using integrator respectively the vectorial trap sequence of frequency real to described second and
Described second empty frequently vectorial trap sequence carries out integral operation, obtains the second real frequency vector integrated value and the second empty frequency vector integration
It is worth and is：
Wherein, R2For the second real vectorial integrated value of frequency；I2For the second empty vectorial integrated value of frequency.L2 is integral and calculating length 2,
Unit dimensionless, L2 are 0.25 times of unit period sequence length.
As shown in figure 5, in one embodiment, the phase determination module 116 can include：
First ratio determination unit 1161, for determining the described first empty vectorial integrated value of frequency and the described first real frequency vector
First ratio of integrated value；
First phase determination unit 1162, for using the opposite number of the arctan function value of first ratio as described in
First phase；
Second ratio determination unit 1163, for determining the described second empty vectorial integrated value of frequency and the described second real frequency vector
Second ratio of integrated value；
Second phase determination unit 1164, for using the opposite number of the arctan function value of second ratio as described in
Second phase.
It is shown below, the first phase and second phase that the phase determination module 116 obtains are respectively：
Wherein, PH1For first phase, unit rad；R1For the first real vectorial integrated value of frequency；I1For the first empty frequency vector product
Score value；PH2For second phase, unit rad；R2For the second real vectorial integrated value of frequency；I2For the second empty vectorial integrated value of frequency；L1
For the integral and calculating length 1 of the dimensionless unit；L2 is the integral and calculating length 2 of the dimensionless unit.
It should be noted that above-mentioned first ratio, the second ratio, just to distinguish each ratio, reduced value is not suitable
Sequence is limited.
After phase determination module 116 obtains first phase and second phase, in one embodiment, the initial phase determines
117 basis of moduleDetermine the first phase of the cosine function modulation sequence
PositionWherein, PH1For first phase, PH2For second phase, N is predetermined sequence length, NsFor truncated sequence length.
According to the initial phase of zero phase modulation sequence and default integer signal period number, all phase difference determining module
118 can basisDetermine all phase difference △ of the cosine function modulation sequence
PH, wherein, C2πTo preset integer signal period number,For the initial phase of the cosine function modulation sequence.
In one embodiment, 119 basis of frequency detection moduleDetermine the frequency of the electric power signal
Rate ω, wherein, N is predetermined sequence length,fnFor preset sample frequency.
Each technical characteristic of embodiment described above can be combined arbitrarily, to make description succinct, not to above-mentioned reality
Apply all possible combination of each technical characteristic in example to be all described, as long as however, the combination of these technical characteristics is not deposited
In contradiction, the scope that this specification is recorded all is considered to be.
Embodiment described above only expresses the several embodiments of the present invention, its description is more specific and detailed, but simultaneously
Cannot therefore it be construed as limiting the scope of the patent.It should be pointed out that come for those of ordinary skill in the art
Say, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the protection of the present invention
Scope.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (8)
1. a kind of frequency power signal detection method modulated according to cosine function, it is characterised in that including step：
According to the lower limit of frequency power signal scope, preset sample frequency and default integer signal period number, tentatively sampled
Sequence length；
The electric power signal is tentatively sampled according to the preliminary sample sequence length, obtains the preliminary of the electric power signal
Sample sequence；
To the preliminary sample sequence into line frequency preliminary survey, the preliminary frequency of the electric power signal is obtained, according to the just cadence
Rate determines reference frequency；
According to the preset sample frequency and the reference frequency, the unit period sequence length of the electric power signal is obtained；
According to the default integer signal period number and the unit period sequence length, predetermined sequence length is obtained；
According to the predetermined sequence length, positive sequence is obtained from the preliminary sample sequence；
The positive sequence is reversely exported, obtains the anti-pleat sequence of the positive sequence；
The positive sequence is added with the anti-pleat sequence, obtains the cosine function modulation sequence of zero initial phase；
The cosine function modulation sequence is truncated, obtains truncated sequence；
The cosine function of the reference frequency and the SIN function of the reference frequency are modulated into sequence with the cosine function respectively
Row are multiplied, and obtain the first real frequency sequence vector and the first empty frequency sequence vector；
The cosine function of the reference frequency and the SIN function of the reference frequency are multiplied with the truncated sequence respectively, obtained
To the second real frequency sequence vector and the second empty frequency sequence vector；
Digital notch is carried out to the described first real frequency sequence vector and the first empty frequency sequence vector respectively, obtains the first real frequency
Vectorial trap sequence and the first empty vectorial trap sequence of frequency；
Integral operation is carried out to the described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency respectively, is obtained
First real frequency vector integrated value and the first empty vectorial integrated value of frequency；
Digital notch is carried out to the described second real frequency sequence vector and the second empty frequency sequence vector respectively, obtains the second real frequency
Vectorial trap sequence and the second empty vectorial trap sequence of frequency；
Integral operation is carried out to the described second real vectorial trap sequence of frequency and the second empty vectorial trap sequence of frequency respectively, is obtained
Second real frequency vector integrated value and the second empty vectorial integrated value of frequency；
According to default phase transition rule, first phase is the described first empty vectorial integrated value of frequency and the described first real frequency vector
The arctan function value of the ratio of integrated value；Second phase is the described second empty vectorial integrated value of frequency and the described second real frequency vector
The arctan function value of the ratio of integrated value；
According to default initial phase transformation rule, the first phase and the second phase are converted into the cosine function sequence
The initial phase of row；The default initial phase transformation rule is：WhereinFor the initial phase, unit rad；PH1 is the first phase；PH2 is the second phase；N is described default
Sequence length；Ns is the truncated sequence length；For the initial phase of the positive sequence；β is the anti-pleat sequence initial phase；
According to default all phase difference transformation rule, the initial phase of the cosine function modulation sequence is linearly calculated, is obtained
Take all phase of the cosine function modulation sequence poor；
According to default frequency power signal transformation rule, all phase difference is taken into ratio with cosine function modulation sequence time span
After obtain the frequency power signal.
2. the frequency power signal detection method according to claim 1 modulated according to cosine function, it is characterised in that root
According to default phase transition rule, the described first empty vectorial integrated value of frequency and the described first real vectorial integrated value of frequency are converted to the
One phase；The step of the described second empty vectorial integrated value of frequency is converted to second phase with the described second real vectorial integrated value of frequency is wrapped
Include：
Determine the first ratio of the described first empty vectorial integrated value of frequency and the described first real vectorial integrated value of frequency；
Using the opposite number of the arctan function value of first ratio as the first phase；
Determine the second ratio of the described second empty vectorial integrated value of frequency and the described second real vectorial integrated value of frequency；
Using the opposite number of the arctan function value of second ratio as the second phase.
3. the frequency power signal detection method according to claim 1 modulated according to cosine function, it is characterised in that root
According toDetermine all phase difference △ PH of the cosine function modulation sequence, wherein, C2πTo be pre-
If integer signal period number,For the initial phase of the cosine function modulation sequence.
4. the frequency power signal detection method according to claim 1 modulated according to cosine function, it is characterised in that root
According toDetermine the frequencies omega of the electric power signal, wherein, N is predetermined sequence length,fnAdopted to be default
Sample frequency.
A kind of 5. frequency power signal detecting system modulated according to cosine function, it is characterised in that including：
Preliminary sample sequence length determination modul, for the lower limit according to frequency power signal scope, preset sample frequency and pre-
If integer signal period number, preliminary sample sequence length is obtained；
Preliminary sample sequence acquisition module, for tentatively being adopted to the electric power signal according to the preliminary sample sequence length
Sample, obtains the preliminary sample sequence of the electric power signal；
Reference frequency determining module, for, into line frequency preliminary survey, obtaining the first of the electric power signal to the preliminary sample sequence
Synchronizing frequency, reference frequency is determined according to the preliminary frequency；
Unit period sequence length determining module, for according to the preset sample frequency and the reference frequency, obtaining described
The unit period sequence length of electric power signal；
Predetermined sequence length determination modul, for according to the default integer signal period number and unit period sequence length
Degree, obtains predetermined sequence length；
Positive retrieval module, for according to the predetermined sequence length, positive sequence to be obtained from the preliminary sample sequence
Row；
Anti- pleat retrieval module, for the positive sequence reversely to be exported, obtains the anti-pleat sequence of the positive sequence；
Cosine function modulation sequence determining module, for the positive sequence to be added with the anti-pleat sequence, obtains zero first phase
The cosine function modulation sequence of position；
Truncated sequence acquisition module, for the cosine function modulation sequence to be truncated, obtains truncated sequence；
Primary vector sequence determining module, for by the SIN function of the cosine function of the reference frequency and the reference frequency
It is multiplied respectively with the cosine function modulation sequence, obtains the first real frequency sequence vector and the first empty frequency sequence vector；
Secondary vector sequence determining module, for by the SIN function of the cosine function of the reference frequency and the reference frequency
It is multiplied respectively with the truncated sequence, obtains the second real frequency sequence vector and the second empty frequency sequence vector；
First trap sequence determining module, for respectively to the described first real frequency sequence vector and the first empty frequency sequence vector
Digital notch is carried out, obtains the first real frequency vector trap sequence and the first empty vectorial trap sequence of frequency；
First integral value determining module, respectively to the described first real vectorial trap sequence of frequency and the first empty vectorial trap sequence of frequency
Row carry out integral operation, obtain the first real frequency vector integrated value and the first empty vectorial integrated value of frequency；
Second trap sequence determining module, for respectively to the described second real frequency sequence vector and the second empty frequency sequence vector
Digital notch is carried out, obtains the second real frequency vector trap sequence and the second empty vectorial trap sequence of frequency；
Second integral value determining module, for being fallen into respectively to the described second real vectorial trap sequence of frequency and the second empty frequency vector
Wave train carries out integral operation, obtains the second real frequency vector integrated value and the second empty vectorial integrated value of frequency；
Phase determination module, for according to default phase transition rule, first phase to be the described first empty vectorial integrated value of frequency
With the arctan function value of the ratio of the described first real vectorial integrated value of frequency；Second phase is the described second empty vectorial integrated value of frequency
With the arctan function value of the ratio of the described second real vectorial integrated value of frequency；
Initial phase determining module, for according to default initial phase transformation rule, by the first phase and described
Second phase is converted to the initial phase of the cosine function sequence；The default initial phase transformation rule is：WhereinFor the initial phase, unit rad；PH1 is described first
Phase；PH2 is the second phase；N is the predetermined sequence length；Ns is the truncated sequence length；For the forward direction
The initial phase of sequence；β is the anti-pleat sequence initial phase；
All phase difference determining module, for according to default all phase difference transformation rule, by the cosine function modulation sequence
Initial phase is linearly calculated, and all phase for obtaining the cosine function modulation sequence is poor；
Frequency detection module, for according to default frequency power signal transformation rule, all phase difference to be modulated with cosine function
Sequence time length obtains the frequency power signal after taking ratio.
6. the frequency power signal detecting system according to claim 5 modulated according to cosine function, it is characterised in that institute
Stating phase determination module includes：
First ratio determination unit, for determining the described first empty vectorial integrated value of frequency and the described first real vectorial integrated value of frequency
First ratio；
First phase determination unit, for using the opposite number of the arctan function value of first ratio as first phase
Position；
Second ratio determination unit, for determining the described second empty vectorial integrated value of frequency and the described second real vectorial integrated value of frequency
Second ratio；
Second phase determination unit, for using the opposite number of the arctan function value of second ratio as second phase
Position.
7. the frequency power signal detecting system according to claim 5 modulated according to cosine function, it is characterised in that institute
State all phase difference determining module according toDetermine the full phase of the cosine function modulation sequence
Potential difference △ PH, wherein, C2πTo preset integer signal period number,For the initial phase of the cosine function modulation sequence.
8. the frequency power signal detecting system according to claim 5 modulated according to cosine function, it is characterised in that institute
State frequency detection module according toDetermine the frequencies omega of the electric power signal, wherein, N is predetermined sequence length,fnFor preset sample frequency.
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