CN104635045A - Power signal frequency detection method and system based on phase modulation - Google Patents

Abstract

The invention discloses a power signal frequency detection method and a power signal frequency detection system based on phase modulation. The method comprises the steps: sampling a power signal according to preset signal time span and preset sampling frequency, so as to obtain an input signal sequence; measuring the frequency of the input signal sequence, so as to obtain the initial frequency of the power signal, and subtracting the input signal sequence and the plus or minus 1 Pi phase-shift sequence of the input signal sequence by using the initial frequency as reference frequency, so as to obtain two phase modulation sequences of which phases change along with the input signal frequency; respectively mixing, filtering and integrating the two phase modulation sequences, so as to obtain the phases of the two phase modulation phases for frequency measurement. By implementing the power signal frequency detection method and the power signal frequency detection system, frequency measurement results with higher accuracy can be obtained.

Description

Based on frequency power signal detection method and the system of phase-modulation

[technical field]

The present invention relates to technical field of electric power, particularly relate to a kind of frequency power signal detection method based on phase-modulation and system.

[background technology]

The frequency measurement, harmonic measure, power measurement etc. of electric system are the measurement of sine parameter in itself.Fourier transforms etc. are the basic skills realizing sine parameter measurement, are widely used in electric system.But along with the development of sinusoidal measuring technique, Fourier transform Problems existing is also more aobvious outstanding, is difficult to the requirement meeting sine parameter high precision computation further.

In power system frequency measurement, there are the frequency measurement or computing method that are in various forms, as zero hands over method, based on the algorithm of filtering, based on Wavelet Transformation Algorithm, based on the algorithm of neural network, the frequency algorithm etc. based on DFT conversion.

But the specified power frequency of operation of power networks is 50Hz, belongs to lower frequency, and above-described frequency measurement method is not high to the frequency measurement accuracy of low frequency signal, and noise immunity is poor, easily cause that the measuring accuracy of sine parameter is low, noise immunity is poor.

[summary of the invention]

Based on this, be necessary for above-described frequency measurement method not high to the frequency measurement accuracy of low frequency signal, and noise immunity is poor, easily cause the problem that the measuring accuracy of sine parameter is low, noise immunity is poor, a kind of frequency power signal detection method based on phase-modulation and system are provided.

Based on a frequency power signal detection method for phase-modulation, comprise the following steps:

According to preset signals time span and default sample frequency, electric power signal is sampled, obtain input signal sequence;

Frequency preliminary survey is carried out to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency;

Described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift by the first transformation rule according to presetting, and generates 1 π sequence length;

According to the second transformation rule preset, described 1 π sequence length and described default sample frequency are converted to phase modulation frequency;

Described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal;

Described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal;

The cosine function of described reference frequency is multiplied with described first phase modulation sequence respectively with the sine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector;

The cosine function of described reference frequency is multiplied with described second phase modulation sequence respectively with the sine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector;

Respectively digital filtering is carried out to described first real number sequence vector and described first imaginary number sequence vector, generate the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence;

Respectively integral operation is carried out to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence, generate the first real number vector product score value and the first imaginary number vector product score value;

Respectively digital filtering is carried out to described second real number sequence vector and described second imaginary number sequence vector, generate the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence;

Integral operation is carried out to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value;

According to the phase transition rule preset, described first imaginary number vector product score value and described first real number vector product score value are converted to first phase;

According to described default phase transition rule, described second imaginary number vector product score value and described second real number vector product score value are converted to second phase;

Described second phase is deducted described first phase, generates phase differential;

According to the frequency inverted rule preset, be the frequency of described electric power signal by described phase differential and phase modulation frequency inverted.

Based on a frequency power signal detection system for phase-modulation, comprising:

Sampling module, for according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence;

Preliminary frequency module, for carrying out frequency preliminary survey to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency;

1 π sequence length module, for described default sample frequency being converted to the sampling interval integer of described reference frequency in 1 π phase shift according to the first transformation rule preset, generates 1 π sequence length;

Phase modulation frequency module, for according to the second transformation rule preset, is converted to phase modulation frequency by described 1 π sequence length and described default sample frequency;

First phase modulation module, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal;

Second phase modulation module, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal;

Primary vector sequence generating module, for being multiplied with described first phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector;

Secondary vector sequence generating module, for being multiplied with described second phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector;

Primary vector filtered sequence generation module, for carrying out digital filtering to described first real number sequence vector and described first imaginary number sequence vector respectively, generates the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence;

Primary vector integrated value generation module, for carrying out integral operation to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence respectively, generates the first real number vector product score value and the first imaginary number vector product score value;

Secondary vector filtered sequence generation module, for carrying out digital filtering to described second real number sequence vector and described second imaginary number sequence vector respectively, generates the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence;

Secondary vector integrated value generation module, for carrying out integral operation to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value;

First phase module, for according to the phase transition rule preset, is converted to first phase by described first imaginary number vector product score value and described first real number vector product score value;

Second phase module, for according to described default phase transition rule, is converted to second phase by described second imaginary number vector product score value and described second real number vector product score value;

Phase difference module, for described second phase is deducted described first phase, generates phase differential;

Described phase differential and phase modulation frequency inverted, for according to the frequency inverted rule preset, are the frequency of described electric power signal by frequency detection module.

The above-mentioned frequency power signal detection method based on phase-modulation and system, according to preset signals time span and default sample frequency, sample to electric power signal, obtains input signal sequence; Measure the frequency of described input signal sequence, obtain the first synchronizing frequency of described electric power signal, and with described just synchronizing frequency for reference frequency to input signal sequence and described input signal sequence ± 1 π phase shift sequence subtracts each other, and obtains two phase modulation sequence that phase place changes with frequency input signal; By carrying out mixing, filtering and integration to described two phase modulation sequence respectively, and then obtaining the phase place of described two phase modulation sequence, carrying out frequency measurement.Pass through ± phase-modulation of 1 π phase shift sequence can effectively restraint speckle or decay subharmonic and subharmonic interference, the mixing interference component in imaginary number sequence vector and real number sequence vector can be suppressed by digital filtering, obtain high-precision imaginary number vector product score value and real number vector product score value, and then the frequency power signal that final acquisition precision is higher.

[accompanying drawing explanation]

Fig. 1 is the schematic flow sheet of frequency power signal detection method first embodiment that the present invention is based on phase-modulation;

Fig. 2 is the amplitude versus frequency characte schematic diagram of phase modulation sequence in the frequency power signal detection method that the present invention is based on phase-modulation;

Fig. 3 is the structural representation of frequency power signal detection system first embodiment that the present invention is based on phase-modulation;

Fig. 4 is the experimental result schematic diagram that the survey frequency relative error of the frequency power signal detection method that the present invention is based on phase-modulation changes with signal jamtosignal.

[embodiment]

In order to make the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the present invention is described in further detail.

Although the step in the present invention arranges with label, and be not used in and limit the precedence of step, the order of step or the execution of certain step need based on other steps unless expressly stated, otherwise the relative rank of step is adjustable.

Refer to Fig. 1, Fig. 1 is the schematic flow sheet of frequency power signal detection method first embodiment based on phase-modulation of the present invention.

The described frequency power signal detection method based on phase-modulation of present embodiment can comprise the following steps:

Step S101, according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence.

Step S102, carries out frequency preliminary survey to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency.

Step S103, described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift by the first transformation rule according to presetting, and generates 1 π sequence length.

Step S104, according to the second transformation rule preset, is converted to phase modulation frequency by described 1 π sequence length and described default sample frequency.

Step S105, subtracts each other described input signal sequence and described input signal sequence in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal.

Step S106, subtracts each other described input signal sequence and described input signal sequence in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal.

Step S107, is multiplied with described first phase modulation sequence with the sine function of described reference frequency respectively by the cosine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector.

Step S108, is multiplied with described second phase modulation sequence with the sine function of described reference frequency respectively by the cosine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector.

Step S109, carries out digital filtering to described first real number sequence vector and described first imaginary number sequence vector respectively, generates the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence.

Step S110, carries out integral operation to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence respectively, generates the first real number vector product score value and the first imaginary number vector product score value.

Step S111, carries out digital filtering to described second real number sequence vector and described second imaginary number sequence vector respectively, generates the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence.

Step S112, carries out integral operation to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value.

Step S113, according to the phase transition rule preset, is converted to first phase by described first imaginary number vector product score value and described first real number vector product score value.

Step S114, according to described default phase transition rule, is converted to second phase by described second imaginary number vector product score value and described second real number vector product score value.

Step S115, deducts described first phase by described second phase, generates phase differential.

Described phase differential and phase modulation frequency inverted, according to the frequency inverted rule preset, are the frequency of described electric power signal by step S116.

Present embodiment, according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence; Measure the frequency of described input signal sequence, obtain the first synchronizing frequency of described electric power signal, and with described just synchronizing frequency for reference frequency to input signal sequence and described input signal sequence ± 1 π phase shift sequence subtracts each other, and obtains two phase modulation sequence that phase place changes with frequency input signal; By carrying out mixing, filtering and integration to described two phase modulation sequence respectively, and then obtaining the phase place of described two phase modulation sequence, carrying out frequency measurement.Pass through ± phase-modulation of 1 π phase shift sequence can effectively restraint speckle or decay subharmonic and subharmonic interference, the mixing interference component in imaginary number sequence vector and real number sequence vector can be suppressed by digital filtering, obtain high-precision imaginary number vector product score value and real number vector product score value, and then the frequency power signal that final acquisition precision is higher.

Wherein, for step S101, the sample devices by electrical network field is sampled to described electric power signal, obtains input signal sequence.

Preferably, in order to ensure certain frequency measurement real-time, power system frequency is often referred to the average frequency of signal at time span 0.2s, and desirable time span equals 0.2s.

Further, electric system rated frequency 50Hz, in order to improve performance, sample frequency much larger than 50Hz, preferably, should be arranged sample frequency and equals f _n=10KHz, sampling interval is expressed as formula (1):

$T_n=\frac{1}{f_n}---\left(1\right);$

In formula, T _nfor sampling interval, unit s; f _nfor described default sample frequency, unit Hz.

Described sample input signal sequence length is expressed as formula (2):

N＝T _sf _n(2)；

In formula, N is input signal sequence length, unit dimensionless, T _sfor the input time that input signal is corresponding, unit s.

Described input signal sequence is expressed as formula (3):

In formula, X _in () is input signal sequence; A is signal amplitude, unit v; ω is signal frequency, unit rad/s; T _nfor sampling interval, unit s; N is series of discrete number, unit dimensionless; N _πit is 1 π sequence length; for initial phase, unit rad.

For step S102, by zero friendship method, frequency preliminary survey is carried out to described input signal sequence, obtain described just synchronizing frequency.Also by other frequency measurement methods that those skilled in the art are usual, frequency preliminary survey is carried out to described input signal sequence.

Described preliminary frequency is expressed as formula (4):

ω _o(4)；

In formula, ω _ofor first synchronizing frequency, unit rad/s;

For step S103, with described just synchronizing frequency for reference frequency follows the tracks of the frequency of described input signal sequence.

Preferably, described reference frequency is expressed as formula (5):

ω _s＝ω _o(5)；

In formula, ω _sfor reference frequency, unit rad/s; ω _ofor first synchronizing frequency, unit rad/s.

In one embodiment, described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift by the first transformation rule according to presetting, and the step generating 1 π sequence length can comprise the following steps:

Obtain the ratio of described default sample frequency and described just synchronizing frequency.

The product of described ratio and π is rounded downwards as immediate integer, generates described 1 π sequence length.

Further, according to described the first default transformation rule formula (6), described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift, generates 1 π sequence length:

$N_{\mathrm{\π}}=\left(\mathrm{int}\right)\frac{\mathrm{\π}}{{\mathrm{\ω}}_s{T}_n}---\left(6\right);$

In formula, N _πfor described 1 π sequence length, unit dimensionless; ω _sfor reference frequency, unit rad/s; T _nsampling interval.

For step S104, described 1 π sequence length is converted to described phase modulation frequency, for revising N by described the second default transformation rule _πthere is the error in 1 sampling interval in integer.

In one embodiment, according to the second transformation rule preset, the step that described 1 π sequence length and described default sample frequency are converted to phase modulation frequency can be comprised the following steps:

Obtain the ratio of described default sample frequency and described 1 π sequence length;

The product obtaining described ratio and π is described phase modulation frequency.

Preferably, by described the second default transformation rule formula (7), described 1 π sequence length is converted to described phase modulation frequency:

${\mathrm{\ω}}_{\mathrm{ph}}=\frac{\mathrm{\π}}{N_{\mathrm{\π}}{T}_n}---\left(7\right);$

In formula, ω _phfor described phase modulation frequency, unit rad/s; N _πfor described 1 π sequence length, unit dimensionless; T _nfor described sampling interval.

Further, the frequency difference of signal frequency and phase modulation frequency is formula (8):

Ω _ph＝ω-ω _ph(8)

In formula, Ω _phfor phase modulation frequency difference, unit rad/s;

The frequency difference of signal frequency and reference frequency is formula (9):

Ω＝ω-ω _s(9)

In formula, Ω is frequency difference, unit rad/s.

For step S105, described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of described 1 π sequence length, generate the first phase modulation sequence that phase place changes with frequency input signal.

Preferably, described first phase modulation sequence is formula (10):

In formula, X _phAn () is described first phase modulation sequence, k _phfor amplitude coefficient, the unit dimensionless of phase modulation sequence.

Further, the amplitude versus frequency characte of described first phase modulation sequence as shown in Figure 2.Wherein signal frequency is 100 π rad/s, and phase modulation sequence has good inhibiting effect to even-order harmonic, also has good attenuation to subharmonic.

For step S106, described-1 π sequence length is the opposite number of described 1 π sequence length.

Preferably, described second phase modulation sequence is formula (11):

In formula, X _phBn () is described second phase modulation sequence.

Further, the amplitude versus frequency characte of described second phase modulation sequence as shown in Figure 2.Wherein signal frequency is 100 π rad/s, and phase modulation sequence has good inhibiting effect to even-order harmonic, also has good attenuation to subharmonic.

For step S107 and step S108, the cosine function of described reference frequency and the sine function of described reference frequency, can be with number reference frequency be frequency cosine function and sine function.Preferably, be multiplied with described first phase modulation sequence or second phase modulation sequence respectively with the sine function of reference frequency with reference to the cosine function of frequency by multiplier, generate the first real number sequence vector and the first imaginary number sequence vector, or generate the second real number sequence vector and the second imaginary number sequence vector.Described multiplier is a kind of frequency mixer.

For step S109, carry out digital filtering by the first real number sequence vector described in digital filter and described first imaginary number sequence vector, generate the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence, filtering mixing interference component.

In one embodiment, digital filtering is to N in described real number sequence vector _tindividual continuous discrete value is added, and then gets its arithmetic mean and exports as filtering.

At N _twhen value is the unit period sequence length of 1/2nd reference frequencies, can suppress 1/2 subharmonic and the impact of all subharmonic, and at N _twhen value is the unit period sequence length of 2/3rds reference frequencies, can suppress 1/3 subharmonic impact.Therefore, digital filtering is made up of the wave filter of two kinds of filtering parameters, and in order to improve the rejection of mixing interference, the wave filter of often kind of filtering parameter is by the identical three stages of digital filtering compositions of parameter.

Filtering parameter N _twhen value is the unit period sequence length of 1/2nd reference frequencies, the first digital filtering is formula (12):

$\begin{array}{c}{X}_1\left(n\right)=\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}\left\{\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}\right[\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}X\left(n\right)\left]\right\}\\ n=\mathrm{0,1,2,3},....,N-3N_{T1}-1\end{array}---\left(12\right);$

In formula, X ₁n () is the first digital filtering output sequence, X (n) is mixed frequency signal sequence, and N is sequence length, N _t1be the first filtering parameter, namely discrete value is added quantity continuously.

N _twhen value is the unit period sequence length of 2/3rds reference frequencies, the second digital filtering is formula (13):

$\begin{array}{c}{X}_2\left(n\right)=\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}\left\{\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}\right[\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}{X}_1\left(n\right)\left]\right\}\\ n=\mathrm{0,1,2,3},....,N-3N_{T1}-3N_{T2}-1\end{array}---\left(13\right);$

In formula, X ₂n () is the second digital filtering output sequence, X ₁n () is the output sequence of described first digital filtering, N _t2be the second filtering parameter, namely discrete value is added quantity continuously.

In other embodiments, also carry out more than three grades digital filterings by the digital filter that the first digital filtering formula is corresponding to described first real number sequence vector or described first imaginary number sequence vector, the digital filter corresponding by the second digital filtering formula carries out more than three grades digital filterings to described first filtering data sequence.

For step S110, respectively integral operation is carried out to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence by integrator, generate the first real number vector product score value and the first imaginary number vector product score value.

Preferably, when not considering that mixing is disturbed, the mixed frequency signal sequence of first phase modulation sequence is formula (14):

In formula, X _r-PhAn real number sequence vector that () is mixed frequency signal sequence, X _i-PhAn imaginary number sequence vector that () is mixed frequency signal sequence.

The sequence of mixed frequency signal sequence after digital filtering is formula (15):

In formula, X _rL-PhAn real number wave-vector filtering sequence that () is mixed frequency signal sequence, X _{iL-PhA (n)}for the imaginary number wave-vector filtering sequence of mixed frequency signal sequence, K (Ω) for digital filtering is in the gain of frequency difference Ω, unit dimensionless, wherein K (0)=1; β (Ω) for digital filtering is in the phase shift of frequency difference Ω, unit rad, wherein β (0)=0.

Under in filtered sequence, mixing interference is suppressed prerequisite completely, the integration type (16) of integrator:

In formula, R _phA(ω _s) be the first real number vector product score value, I _phA(ω _s) be the first imaginary number vector product score value; L is integral sequence length, unit dimensionless.

Step S111 and step S112 is corresponding to step S109 and step S110 respectively.

For step S113 and step S114, described default phase transition rule can be the usual phase inversion process in this area.

In one embodiment, according to the phase transition rule preset, the step that described first imaginary number vector product score value and described first real number vector product score value are converted to first phase is comprised the following steps:

Obtain the ratio of described first imaginary number vector product score value and described first real number vector product score value;

Obtain the opposite number of the arctan function value of described ratio, generate described first phase.

In another embodiment, according to the phase transition rule preset, the step that described second imaginary number vector product score value and described second real number vector product score value are converted to second phase is comprised the following steps:

Obtain the ratio of described second imaginary number vector product score value and described second real number vector product score value;

Obtain the opposite number of the arctan function value of described ratio, generate described second phase.

Preferably, first phase and second phase is obtained respectively by formula (17) and formula (18):

Wherein, PH _afor first phase, PH _bfor second phase, R _phB(ω _s) be the second real number vector product score value, I _phB(ω _s) be the second imaginary number vector product score value.

For step S115, obtain phase differential by following formula (19):

$\mathrm{\ΔPH}\left({\mathrm{\ω}}_s\right)={\mathrm{PH}}_B\left({\mathrm{\ω}}_s\right)-{\mathrm{PH}}_A\left({\mathrm{\ω}}_s\right)=\frac{{\mathrm{\Ω}}_{\mathrm{ph}}\mathrm{\π}}{{\mathrm{\ω}}_{\mathrm{ph}}}---\left(19\right);$

Wherein, Δ PH (ω _s) be phase differential.

For step S116, be the frequency of described electric power signal by described phase differential and described phase modulation frequency inverted by the frequency detection equipment in electrical network field.

In one embodiment, according to the frequency inverted rule preset, the step being the frequency of described electric power signal by described phase differential and phase modulation frequency inverted comprises the following steps:

The ratio obtaining described phase differential and π generates phase place ratio.

Described phase place ratio is added with described phase modulation frequency with described phase modulation frequency multiplication again, generates the frequency of described electric power signal.

Preferably, by formula (20) by described phase differential and described phase modulation frequency inverted be the frequency of described electric power signal:

$\mathrm{\ω}=\frac{\mathrm{\ΔPH}\left({\mathrm{\ω}}_s\right)}{\mathrm{\π}}{\mathrm{\ω}}_{\mathrm{ph}}+{\mathrm{\ω}}_{\mathrm{ph}}---\left(20\right);$

Wherein, ω is the frequency of electric power signal.

Refer to Fig. 3, Fig. 3 is the structural representation of frequency power signal detection system first embodiment based on phase-modulation of the present invention.

The described frequency power signal detection system based on phase-modulation of present embodiment can comprise sampling module 1010, preliminary frequency module 1020, 1 π sequence length module 1030, phase modulation frequency module 1040, first phase modulation module 1050, second phase modulation module 1060, primary vector sequence generating module 1080, secondary vector sequence generating module 1090, primary vector filtered sequence generation module 1100, primary vector integrated value generation module 1110, secondary vector filtered sequence generation module 1120, secondary vector integrated value generation module 1130, first phase module 1140, second phase module 1150, phase difference module 1160, frequency measuring block 1170, wherein:

Sampling module 1010, for according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence.

Preliminary frequency module 1020, for carrying out frequency preliminary survey to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency.

1 π sequence length module 1030, for described default sample frequency being converted to the sampling interval integer of described reference frequency in 1 π phase shift according to the first transformation rule preset, generates 1 π sequence length.

Phase modulation frequency module 1040, for according to the second transformation rule preset, is converted to phase modulation frequency by described 1 π sequence length and described default sample frequency.

First phase modulation module 1050, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal.

Second phase modulation module 1060, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal.

Primary vector sequence generating module 1080, for being multiplied with described first phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector.

Secondary vector sequence generating module 1090, for being multiplied with described second phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector.

Primary vector filtered sequence generation module 1100, for carrying out digital filtering to described first real number sequence vector and described first imaginary number sequence vector respectively, generates the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence.

Primary vector integrated value generation module 1110, for carrying out integral operation to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence respectively, generates the first real number vector product score value and the first imaginary number vector product score value.

Secondary vector filtered sequence generation module 1120, for carrying out digital filtering to described second real number sequence vector and described second imaginary number sequence vector respectively, generates the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence.

Secondary vector integrated value generation module 1130, for carrying out integral operation to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value.

First phase module 1140, for according to the phase transition rule preset, is converted to first phase by described first imaginary number vector product score value and described first real number vector product score value.

Second phase module 1150, for according to described default phase transition rule, is converted to second phase by described second imaginary number vector product score value and described second real number vector product score value.

Phase difference module 1160, for described second phase is deducted described first phase, generates phase differential.

Described phase differential and phase modulation frequency inverted, for according to the frequency inverted rule preset, are the frequency of described electric power signal by frequency detection module 1170.

Present embodiment, according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence; Measure the frequency of described input signal sequence, obtain the first synchronizing frequency of described electric power signal, and with described just synchronizing frequency for reference frequency to input signal sequence and described input signal sequence ± 1 π phase shift sequence subtracts each other, and obtains two phase modulation sequence that phase place changes with frequency input signal; By carrying out mixing, filtering and integration to described two phase modulation sequence respectively, and then obtaining the phase place of described two phase modulation sequence, carrying out frequency measurement.Pass through ± phase-modulation of 1 π phase shift sequence can effectively restraint speckle or decay subharmonic and subharmonic interference, the mixing interference component in imaginary number sequence vector and real number sequence vector can be suppressed by digital filtering, obtain high-precision imaginary number vector product score value and real number vector product score value, and then the frequency power signal that final acquisition precision is higher.

Wherein, for sampling module 1010, the sample devices by electrical network field is sampled to described electric power signal, obtains input signal sequence.

Preferably, in order to ensure certain frequency measurement real-time, power system frequency is often referred to the average frequency of signal at time span 0.2s, and desirable time span equals 0.2s.

Further, electric system rated frequency 50Hz, in order to improve performance, sample frequency much larger than 50Hz, preferably, should be arranged sample frequency and equals f _n=10KHz, sampling interval is expressed as formula (1):

$T_n=\frac{1}{f_n}---\left(1\right);$

In formula, T _nfor sampling interval, unit s; f _nfor described default sample frequency, unit Hz.

Described sample input signal sequence length is expressed as formula (2):

N＝T _sf _n(2)；

In formula, N is input signal sequence length, unit dimensionless, T _sfor the input time that input signal is corresponding, unit s.

Described input signal sequence is expressed as formula (3):

In formula, X _in () is input signal sequence; A is signal amplitude, unit v; ω is signal frequency, unit rad/s; T _nfor sampling interval, unit s; N is series of discrete number, unit dimensionless; N _πit is 1 π sequence length; for initial phase, unit rad.

For preliminary frequency module 1020, by zero friendship method, frequency preliminary survey is carried out to described input signal sequence, obtain described just synchronizing frequency.Also by other frequency measurement methods that those skilled in the art are usual, frequency preliminary survey is carried out to described input signal sequence.

Described preliminary frequency is expressed as formula (4):

ω _o(4)；

In formula, ω _ofor first synchronizing frequency, unit rad/s;

For 1 π sequence length module 1030, with described just synchronizing frequency for reference frequency follows the tracks of the frequency of described input signal sequence.

Preferably, described reference frequency is expressed as formula (5):

ω _s＝ω _o(5)；

In formula, ω _sfor reference frequency, unit rad/s; ω _ofor first synchronizing frequency, unit rad/s.

In one embodiment, 1 π sequence length module 1030 can be used for:

Obtain the ratio of described default sample frequency and described just synchronizing frequency.

The product of described ratio and π is rounded downwards as immediate integer, generates described 1 π sequence length.

Further, according to described the first default transformation rule formula (6), described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift, generates 1 π sequence length:

$N_{\mathrm{\π}}=\left(\mathrm{int}\right)\frac{\mathrm{\π}}{{\mathrm{\ω}}_s{T}_n}---\left(6\right);$

In formula, N _πfor described 1 π sequence length, unit dimensionless; ω _sfor reference frequency, unit rad/s; T _nsampling interval.

For phase modulation frequency module 1040, described 1 π sequence length is converted to described phase modulation frequency, for revising N by described the second default transformation rule _πthere is the error in 1 sampling interval in integer.

In one embodiment, phase modulation frequency module 1040 can be used for:

Obtain the ratio of described default sample frequency and described 1 π sequence length;

The product obtaining described ratio and π is described phase modulation frequency.

Preferably, by described the second default transformation rule formula (7), described 1 π sequence length is converted to described phase modulation frequency:

${\mathrm{\ω}}_{\mathrm{ph}}=\frac{\mathrm{\π}}{N_{\mathrm{\π}}{T}_n}---\left(7\right);$

In formula, ω _phfor described phase modulation frequency, unit rad/s; N _πfor described 1 π sequence length, unit dimensionless; T _nfor described sampling interval.

Further, the frequency difference of signal frequency and phase modulation frequency is formula (8):

Ω _ph＝ω-ω _ph(8)

In formula, Ω _phfor phase modulation frequency difference, unit rad/s;

The frequency difference of signal frequency and reference frequency is formula (9):

Ω＝ω-ω _s(9)

In formula, Ω is frequency difference, unit rad/s.

For first phase modulation module 1050, described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of described 1 π sequence length, generate the first phase modulation sequence that phase place changes with frequency input signal.

Preferably, described first phase modulation sequence is formula (10):

In formula, X _phAn () is described first phase modulation sequence, k _phfor amplitude coefficient, the unit dimensionless of phase modulation sequence.

Further, the amplitude versus frequency characte of described first phase modulation sequence as shown in Figure 2.Wherein signal frequency is 100 π rad/s, and phase modulation sequence has good inhibiting effect to even-order harmonic, also has good attenuation to subharmonic.

For second phase modulation module 1060, described-1 π sequence length is the opposite number of described 1 π sequence length.

Preferably, described second phase modulation sequence is formula (11):

In formula, X _phBn () is described second phase modulation sequence.

Further, the amplitude versus frequency characte of described second phase modulation sequence as shown in Figure 2.Wherein signal frequency is 100 π rad/s, and phase modulation sequence has good inhibiting effect to even-order harmonic, also has good attenuation to subharmonic.

For primary vector sequence generating module 1080 and secondary vector sequence generating module 1090, preferably, be multiplied with described first phase modulation sequence or second phase modulation sequence respectively with the sine function of reference frequency with reference to the cosine function of frequency by multiplier, generate the first real number sequence vector and the first imaginary number sequence vector, or generate the second real number sequence vector and the second imaginary number sequence vector.Described multiplier is a kind of frequency mixer.

For primary vector filtered sequence generation module 1100, digital filtering is carried out by the first real number sequence vector described in digital filter and described first imaginary number sequence vector, generate the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence, filtering mixing interference component.

In one embodiment, digital filtering is to N in described real number sequence vector _tindividual continuous discrete value is added, and then gets its arithmetic mean and exports as filtering.

At N _twhen value is the unit period sequence length of 1/2nd reference frequencies, can suppress 1/2 subharmonic and the impact of all subharmonic, and at N _twhen value is the unit period sequence length of 2/3rds reference frequencies, can suppress 1/3 subharmonic impact.Therefore, digital filtering is made up of the wave filter of two kinds of filtering parameters, and in order to improve the rejection of mixing interference, the wave filter of often kind of filtering parameter is by the identical three stages of digital filtering compositions of parameter.

Filtering parameter N _twhen value is the unit period sequence length of 1/2nd reference frequencies, the first digital filtering is formula (12):

$\begin{array}{c}{X}_1\left(n\right)=\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}\left\{\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}\right[\frac{1}{N_{T1}}\underset{n}{\overset{N_{T1}}{\mathrm{\Σ}}}X\left(n\right)\left]\right\}\\ n=\mathrm{0,1,2,3},....,N-3N_{T1}-1\end{array}---\left(12\right);$

In formula, X ₁n () is the first digital filtering output sequence, X (n) is mixed frequency signal sequence, and N is sequence length, N _t1be the first filtering parameter, namely discrete value is added quantity continuously.

N _twhen value is the unit period sequence length of 2/3rds reference frequencies, the second digital filtering is formula (13):

$\begin{array}{c}{X}_2\left(n\right)=\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}\left\{\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}\right[\frac{1}{N_{T2}}\underset{n}{\overset{N_{T2}}{\mathrm{\Σ}}}{X}_1\left(n\right)\left]\right\}\\ n=\mathrm{0,1,2,3},....,N-3N_{T1}-3N_{T2}-1\end{array}---\left(13\right);$

In formula, X ₂n () is the second digital filtering output sequence, X ₁n () is the output sequence of described first digital filtering, N _t2be the second filtering parameter, namely discrete value is added quantity continuously.

In other embodiments, also carry out more than three grades digital filterings by the digital filter that the first digital filtering formula is corresponding to described first real number sequence vector or described first imaginary number sequence vector, the digital filter corresponding by the second digital filtering formula carries out more than three grades digital filterings to described first filtering data sequence.

For primary vector integrated value generation module 1110, respectively integral operation is carried out to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence by integrator, generate the first real number vector product score value and the first imaginary number vector product score value.

Preferably, when not considering that mixing is disturbed, the mixed frequency signal sequence of first phase modulation sequence is formula (14):

In formula, X _r-PhAn real number sequence vector that () is mixed frequency signal sequence, X _i-PhAn imaginary number sequence vector that () is mixed frequency signal sequence.

The sequence of mixed frequency signal sequence after digital filtering is formula (15):

In formula, X _rL-PhAn real number wave-vector filtering sequence that () is mixed frequency signal sequence, X _{iL-PhA (}n) be the imaginary number wave-vector filtering sequence of mixed frequency signal sequence, K (Ω) for digital filtering is in the gain of frequency difference Ω, unit dimensionless, wherein K (0)=1; β (Ω) for digital filtering is in the phase shift of frequency difference Ω, unit rad, wherein β (0)=0.

Under in filtered sequence, mixing interference is suppressed prerequisite completely, the integration type (16) of integrator:

In formula, R _phA(ω _s) be the first real number vector product score value, I _phA(ω _s) be the first imaginary number vector product score value; L is integral sequence length, unit dimensionless.

Secondary vector filtered sequence generation module 1120, secondary vector integrated value generation module 1130 are corresponding to step S110 and step S111 respectively.

For first phase module 1140 and second phase module 1150, described default phase transition rule can be the usual phase inversion process in this area.

In one embodiment, first phase module 1140 can be used for:

Obtain the ratio of described first imaginary number vector product score value and described first real number vector product score value;

Obtain the opposite number of the arctan function value of described ratio, generate described first phase.

In another embodiment, second phase module 1150 can be used for:

Obtain the ratio of described second imaginary number vector product score value and described second real number vector product score value;

Obtain the opposite number of the arctan function value of described ratio, generate described second phase.

Preferably, first phase module 1140 and second phase module 1150 can obtain first phase and second phase respectively respectively by formula (17) and formula (18):

Wherein, PH _afor first phase, PH _bfor second phase, R _phB(ω _s) be the second real number vector product score value, I _phB(ω _s) be the second imaginary number vector product score value.

For, phase difference module 1160, obtain phase differential by following formula (19):

$\mathrm{\ΔPH}\left({\mathrm{\ω}}_s\right)={\mathrm{PH}}_B\left({\mathrm{\ω}}_s\right)-{\mathrm{PH}}_A\left({\mathrm{\ω}}_s\right)=\frac{{\mathrm{\Ω}}_{\mathrm{ph}}\mathrm{\π}}{{\mathrm{\ω}}_{\mathrm{ph}}}---\left(19\right);$

Wherein, Δ PH (ω _s) be phase differential.

For frequency measuring block 1170, be the frequency of described electric power signal by described phase differential and described phase modulation frequency inverted by the frequency detection equipment in electrical network field.

In one embodiment, frequency measuring block 1170 can be used for:

The ratio obtaining described phase differential and π generates phase place ratio.

Described phase place ratio is added with described phase modulation frequency with described phase modulation frequency multiplication again, generates the frequency of described electric power signal.

Preferably, described phase differential and described phase modulation frequency inverted are the frequency of described electric power signal by formula (20) by frequency measuring block 1170:

$\mathrm{\ω}=\frac{\mathrm{\ΔPH}\left({\mathrm{\ω}}_s\right)}{\mathrm{\π}}{\mathrm{\ω}}_{\mathrm{ph}}+{\mathrm{\ω}}_{\mathrm{ph}}---\left(20\right);$

Wherein, ω is the frequency of electric power signal.

Refer to Fig. 4, Fig. 4 is the experimental result schematic diagram that the survey frequency relative error of the frequency power signal detection method that the present invention is based on phase-modulation changes with signal jamtosignal.

The present invention is based in the frequency power signal detection method of phase-modulation, described default sample frequency is 5kHz, input signal time 0.25s, reference frequency 50.125Hz, the experimental result that survey frequency relative error Ferr (N:S) changes with signal jamtosignal as shown in Figure 4, wherein, 10 can be realized when jamtosignal-60dB ^-6the frequency computation part of order of magnitude precision.

The above embodiment only have expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (10)

1., based on a frequency power signal detection method for phase-modulation, it is characterized in that, comprise the following steps:

According to preset signals time span and default sample frequency, electric power signal is sampled, obtain input signal sequence;

Frequency preliminary survey is carried out to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency.

Described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift by the first transformation rule according to presetting, and generates 1 π sequence length;

According to the second transformation rule preset, described 1 π sequence length and described default sample frequency are converted to phase modulation frequency;

Described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal;

Described input signal sequence and described input signal sequence are subtracted each other in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal;

The cosine function of described reference frequency is multiplied with described first phase modulation sequence respectively with the sine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector;

The cosine function of described reference frequency is multiplied with described second phase modulation sequence respectively with the sine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector;

Respectively digital filtering is carried out to described first real number sequence vector and described first imaginary number sequence vector, generate the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence;

Respectively integral operation is carried out to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence, generate the first real number vector product score value and the first imaginary number vector product score value;

Respectively digital filtering is carried out to described second real number sequence vector and described second imaginary number sequence vector, generate the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence;

Integral operation is carried out to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value;

According to the phase transition rule preset, described first imaginary number vector product score value and described first real number vector product score value are converted to first phase;

According to described default phase transition rule, described second imaginary number vector product score value and described second real number vector product score value are converted to second phase;

Described second phase is deducted described first phase, generates phase differential;

According to the frequency inverted rule preset, be the frequency of described electric power signal by described phase differential and phase modulation frequency inverted.

2. the frequency power signal detection method based on phase-modulation according to claim 1, is characterized in that, according to the second transformation rule preset, the step that described 1 π sequence length and described default sample frequency are converted to phase modulation frequency is comprised the following steps:

Obtain the ratio of described default sample frequency and described 1 π sequence length;

The product obtaining described ratio and π is described phase modulation frequency.

3. the frequency power signal detection method based on phase-modulation according to claim 1, it is characterized in that, according to the first transformation rule preset, described default sample frequency is converted to the sampling interval integer of described reference frequency in 1 π phase shift, the step generating 1 π sequence length comprises the following steps:

Obtain the ratio of described default sample frequency and described just synchronizing frequency;

The product of described ratio and π is rounded downwards as immediate integer, generates described 1 π sequence length.

4. the frequency power signal detection method based on phase-modulation according to claim 1, it is characterized in that, according to the phase transition rule preset, the step that described first imaginary number vector product score value and described first real number vector product score value are converted to first phase is comprised the following steps:

Obtain the ratio of described first imaginary number vector product score value and described first real number vector product score value;

Obtain the opposite number of the arctan function value of described ratio, generate described first phase.

5. the frequency power signal detection method based on phase-modulation as claimed in any of claims 1 to 4, it is characterized in that, according to the frequency inverted rule preset, the step being the frequency of described electric power signal by described phase differential and phase modulation frequency inverted comprises the following steps:

The ratio obtaining described phase differential and π generates phase place ratio;

Described phase place ratio is added with described phase modulation frequency with described phase modulation frequency multiplication again, generates the frequency of described electric power signal.

6., based on a frequency power signal detection system for phase-modulation, it is characterized in that, comprising:

Sampling module, for according to preset signals time span and default sample frequency, samples to electric power signal, obtains input signal sequence;

Preliminary frequency module, for carrying out frequency preliminary survey to described input signal sequence, generates the first synchronizing frequency of described electric power signal, with the described just given reference frequency of synchronizing frequency.

1 π sequence length module, for described default sample frequency being converted to the sampling interval integer of described reference frequency in 1 π phase shift according to the first transformation rule preset, generates 1 π sequence length;

Phase modulation frequency module, for according to the second transformation rule preset, is converted to phase modulation frequency by described 1 π sequence length and described default sample frequency;

First phase modulation module, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of described 1 π sequence length, generates the first phase modulation sequence that phase place changes with frequency input signal;

Second phase modulation module, for described input signal sequence and described input signal sequence being subtracted each other in the phase shift sequence of-1 π sequence length, generates the second phase modulation sequence that phase place changes with frequency input signal;

Primary vector sequence generating module, for being multiplied with described first phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the first real number sequence vector and the first imaginary number sequence vector;

Secondary vector sequence generating module, for being multiplied with described second phase modulation sequence respectively with the sine function of described reference frequency by the cosine function of described reference frequency, generates the second real number sequence vector and the second imaginary number sequence vector;

Primary vector filtered sequence generation module, for carrying out digital filtering to described first real number sequence vector and described first imaginary number sequence vector respectively, generates the first real number wave-vector filtering sequence and the first imaginary number wave-vector filtering sequence;

Primary vector integrated value generation module, for carrying out integral operation to described first real number wave-vector filtering sequence and described first imaginary number wave-vector filtering sequence respectively, generates the first real number vector product score value and the first imaginary number vector product score value;

Secondary vector filtered sequence generation module, for carrying out digital filtering to described second real number sequence vector and described second imaginary number sequence vector respectively, generates the second real number wave-vector filtering sequence and the second imaginary number wave-vector filtering sequence;

Secondary vector integrated value generation module, for carrying out integral operation to described second real number wave-vector filtering sequence and described second imaginary number wave-vector filtering sequence, generates the second real number vector product score value and the second imaginary number vector product score value;

First phase module, for according to the phase transition rule preset, is converted to first phase by described first imaginary number vector product score value and described first real number vector product score value;

Second phase module, for according to described default phase transition rule, is converted to second phase by described second imaginary number vector product score value and described second real number vector product score value;

Phase difference module, for described second phase is deducted described first phase, generates phase differential;

Described phase differential and phase modulation frequency inverted, for according to the frequency inverted rule preset, are the frequency of described electric power signal by frequency detection module.

7. the frequency power signal detection system based on phase-modulation according to claim 6, is characterized in that, described phase modulation frequency module is also for obtaining the ratio of described default sample frequency and described 1 π sequence length; The product obtaining described ratio and π is described phase modulation frequency.

8. the frequency power signal detection system based on phase-modulation according to claim 6, is characterized in that, described 1 π sequence length module is also for obtaining the ratio of described default sample frequency and described just synchronizing frequency; The product of described ratio and π is rounded downwards as immediate integer, generates described 1 π sequence length.

9. the frequency power signal detection system based on phase-modulation according to claim 6, is characterized in that, described first phase module is also for obtaining the ratio of described first imaginary number vector product score value and described first real number vector product score value; Obtain the opposite number of the arctan function value of described ratio, generate described first phase.

10. according to the frequency power signal detection system based on phase-modulation in claim 6 to 9 described in any one, it is characterized in that, the ratio of described frequency detection module also for obtaining described phase differential and π generates phase place ratio; Described phase place ratio is added with described phase modulation frequency with described phase modulation frequency multiplication again, generates the frequency of described electric power signal.