CN104502701A - Method and system for detecting electric power signal frequency based on phase modulation - Google Patents

Abstract

The invention discloses a method and a system for detecting electric power signal frequency based on phase modulation. The method comprises the following steps of sampling electric power signals according to preset signal time duration and preset sampling frequency to obtain an input signal sequence; measuring the frequency of the input signal sequence to obtain the initial frequency of the electric power signals, and subtracting the input signal sequence from the +/- 1 phi phase-shift sequence of the input signal sequence by taking the initial frequency as a reference frequency to obtain two phase modulation sequences of which the phase positions vary along with the input signal frequency, wherein the two phase modulation sequences are used for frequency measurement. Through the implementation of the method and the system, the frequency measurement result with higher precision can be obtained.

Description

The method and system of frequency power signal is detected based on phase-modulation

[technical field]

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

[background technology]

Power frequency is measured significant to electric system, and the specified power frequency of operation of power networks is 50Hz, belongs to lower frequency.Can according to phase difference measurement low frequency signal frequency, ultimate principle is, gets data sequence that 2 spacer segments separate, phase difference measurement frequency according to 2 segment data sequences.

But there is subharmonic and subharmonic interference in the electric power signal of reality, described 2 segment data sequences do not have the filtering characteristic of frequency domain, can not suppress or decay subharmonic and subharmonic interference, can reduce frequency measurement accuracy.

[summary of the invention]

Based on this, be necessary for the low problem of said frequencies measuring method frequency measurement accuracy, a kind of method and system detecting frequency power signal based on phase-modulation is provided.

Detect a method for frequency power signal based on 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 correction reference frequency;

Described input signal sequence and described input signal 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 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;

Obtain the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence;

According to the frequency inverted rule preset, described phase differential and described correction reference frequency are converted to the frequency of described electric power signal.

Detect a system for frequency power signal based on 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;

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

Reference frequency correcting module, for according to the second transformation rule preset, is converted to correction reference 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 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 is transferred to another post module, for described input signal sequence and described input signal 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;

Phase difference module, for the phase differential of the phase place of the phase place and described second phase modulation sequence that obtain described first phase modulation sequence;

Frequency measuring block, for according to the frequency inverted rule preset, is converted to the frequency of described electric power signal by described phase differential and described correction reference frequency.

The above-mentioned method and system detecting frequency power signal based on phase-modulation, sampling interval integer corresponding to described 1 π phase shift is calculated according to reference frequency, it is 1 π sequence length, and according to described 1 π sequence length, obtain described correction reference frequency, described input signal sequence and described input signal are subtracted each other in the phase shift sequence of ± 1 π sequence length, generate first phase modulation sequence and second phase modulation sequence that phase place changes with frequency input signal, can effectively restraint speckle or decay subharmonic and subharmonic interference, described two phase modulation sequence are used for frequency measurement, the frequency measurement of degree of precision can be obtained.

[accompanying drawing explanation]

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

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

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

Fig. 4 the present invention is based on the experimental result schematic diagram that phase-modulation detects the survey frequency relative error t change in time of the method for frequency power signal.

[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 detecting method first embodiment of frequency power signal based on phase-modulation of the present invention.

The described method based on phase-modulation detection frequency power signal 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.

Step S103, 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.

Step S104, according to the second transformation rule preset, is converted to correction reference 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 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 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, obtains the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence.

Step S108, according to the frequency inverted rule preset, is converted to the frequency of described electric power signal by described phase differential and described correction reference frequency.

Present embodiment, sampling interval integer corresponding to described 1 π phase shift is calculated according to reference frequency, it is 1 π sequence length, and according to described 1 π sequence length, , obtain described correction reference frequency, described input signal sequence and described input signal are subtracted each other in the phase shift sequence of ± 1 π sequence length, generate first phase modulation sequence and second phase modulation sequence that phase place changes with frequency input signal, can effectively restraint speckle or decay subharmonic and subharmonic interference, described two phase modulation sequence are used for frequency measurement, the frequency measurement of degree of precision can be obtained.

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::

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

In formula, N _πfor described 1 π sequence length, unit dimensionless; ω _sfor first synchronizing frequency, unit rad/s; f _nfor described default sample frequency, unit Hz.

For step S104, described 1 π sequence length is converted to described correction reference 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, described 1 π sequence length and described default sample frequency being converted to the step revising reference frequency can comprise 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 correction reference frequency.

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

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

In formula, ω _setfor described correction reference frequency, unit rad/s; N _πfor described 1 π sequence length, unit dimensionless; f _nfor described default sample frequency, unit Hz.

For step S105, described input signal sequence and described input signal 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 (8):

In formula, X _ph1n () is described first phase modulation sequence.

The first phase of described first phase modulation sequence is formula (9):

${\mathrm{Ph}}_1=-\frac{\mathrm{\ω}}{{2\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(9\right);$

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 (10):

In formula, X _ph2n () is described second phase modulation sequence.

The second phase of described second phase modulation sequence is formula (11):

${\mathrm{Ph}}_2=\frac{\mathrm{\ω}}{{2\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(11\right);$

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, by the phase place acquisition methods that electrical network field is usual, obtain the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence.

In one embodiment, the step obtaining the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence can comprise the following steps:

Plural integral and calculating is carried out to described first phase modulation sequence, generates first phase.

Plural integral and calculating is carried out to described second phase modulation sequence, generates second phase.

Obtain the difference of described first phase and described second phase, generate described phase differential.

Preferably, described phase differential is formula (12):

$\mathrm{\ΔPh}={\mathrm{Ph}}_2-{\mathrm{Ph}}_1={\mathrm{Ph}}_2-{\mathrm{Ph}}_2=\frac{\mathrm{\ω}}{{\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(12\right);$

In formula, PH ₂for described second phase, unit rad; PH ₁for described first phase, unit rad; Ph ₂for described second phase phase modulation, unit rad; Ph ₁for described first phase phase modulation, unit rad; Phase differential described in △ PH, unit rad.

For step S108, by the frequency detection equipment in electrical network field, described phase differential and described correction reference frequency are converted to the frequency of described electric power signal.

In one embodiment, according to the frequency inverted rule preset, the step that described phase differential and described correction reference frequency are converted to the frequency of described electric power signal can be comprised the following steps:

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

Described phase place ratio is multiplied with described correction reference frequency, generates the frequency of described electric power signal.

Preferably, the frequency of described electric power signal can be obtained according to described default frequency inverted formal style (13):

$\mathrm{\ω}=\frac{\mathrm{\ΔPH}}{\mathrm{\π}}{\mathrm{\ω}}_{\mathrm{set}}---\left(13\right);$

In formula, ω is the frequency of described input signal sequence, unit rad/s; ω _setfor described correction reference frequency, unit rad/s.

In other embodiments, the usual plural integration method of those skilled in the art also can be adopted to obtain the phase place of described phase modulation sequence.

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

The described system based on phase-modulation detection frequency power signal of present embodiment can comprise sampling module 1010, preliminary frequency measuring block 1020,1 π sequence length module 1030, reference frequency correcting module 1040, first phase modulation module 1050, second phase modulation module 1060, phase difference module 1070 and frequency measuring block 1080, 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.

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

Reference frequency correcting module 1040, for according to the second transformation rule preset, is converted to correction reference 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 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 is transferred to another post module 1060, for described input signal sequence and described input signal 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.

Phase difference module 1070, for the phase differential of the phase place of the phase place and described second phase modulation sequence that obtain described first phase modulation sequence.

Frequency measuring block 1080, for according to the frequency inverted rule preset, is converted to the frequency of described electric power signal by described phase differential and described correction reference frequency.

Present embodiment, sampling interval integer corresponding to described 1 π phase shift is calculated according to reference frequency, it is 1 π sequence length, and according to described 1 π sequence length, obtain described correction reference frequency, described input signal sequence and described input signal are subtracted each other in the phase shift sequence of ± 1 π sequence length, generate first phase modulation sequence and second phase modulation sequence that phase place changes with frequency input signal, can effectively restraint speckle or decay subharmonic and subharmonic interference, described two phase modulation sequence are used for frequency measurement, the frequency measurement of degree of precision can be obtained.

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 measuring block 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.

Preferably, 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.By the sampling interval checkout equipment in electrical network field, described default sample frequency is converted to the sampling interval number integer that 1 π phase shift is corresponding.

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 also 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::

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

In formula, N _πfor described 1 π sequence length, unit dimensionless; ω _sfor first synchronizing frequency, unit rad/s; f _nfor described default sample frequency, unit Hz.

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

In one embodiment, reference frequency correcting module 1040 also 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 correction reference frequency.

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

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

In formula, ω _setfor described correction reference frequency, unit rad/s; N _πfor described 1 π sequence length, unit dimensionless; f _nfor described default sample frequency, unit Hz.

For first phase modulation module 1050, described input signal sequence and described input signal 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 (8):

In formula, X _ph1n () is described first phase modulation sequence.

The phase place of described first phase modulation sequence is formula (9):

${\mathrm{Ph}}_1=-\frac{\mathrm{\ω}}{{2\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(9\right);$

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 (10):

In formula, X _ph2n () is described second phase modulation sequence.

The phase place of described second phase modulation sequence is formula (11):

${\mathrm{Ph}}_2=\frac{\mathrm{\ω}}{{2\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(11\right);$

Further, the amplitude versus frequency characte of described second phase modulation sequence as figure, shown in 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 phase difference module 1070, obtain the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence.

In one embodiment, phase difference module 1070 also can be used for:

Plural integral and calculating is carried out to described first phase modulation sequence, generates first phase.

Plural integral and calculating is carried out to described second phase modulation sequence, generates second phase.

Obtain the difference of described first phase and described second phase, generate described phase differential.

Preferably, described phase differential is obtained by following formula (12):

$\mathrm{\ΔPh}={\mathrm{Ph}}_2-{\mathrm{Ph}}_1={\mathrm{Ph}}_2-{\mathrm{Ph}}_2=\frac{\mathrm{\ω}}{{\mathrm{\ω}}_{\mathrm{set}}}\mathrm{\π}---\left(12\right);$

In formula, PH ₂for described second phase, unit rad; PH ₁for described first phase, unit rad; Ph ₂for described second phase phase modulation, unit rad; Ph ₁for described first phase phase modulation, unit rad; Phase differential described in △ PH, unit rad.

For frequency measuring block 1080, by the frequency detection equipment in electrical network field, described phase differential and described correction reference frequency are converted to the frequency of described electric power signal.

In one embodiment, described frequency measuring block also for:

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

Described phase place ratio is multiplied with described correction reference frequency, generates the frequency of described electric power signal.

Preferably, frequency measuring block 1080 can obtain the frequency of described electric power signal according to described default frequency inverted formal style (13):

$\mathrm{\ω}=\frac{\mathrm{\ΔPH}}{\mathrm{\π}}{\mathrm{\ω}}_{\mathrm{set}}---\left(13\right);$

In formula, ω is the frequency of described input signal sequence, unit rad/s; ω _setfor described correction reference frequency, unit rad/s.

In other embodiments, the usual phase calculation method of those skilled in the art also can be adopted to obtain the phase place of described phase modulation sequence.

Refer to Fig. 4, Fig. 4 the present invention is based on the experimental result schematic diagram that phase-modulation detects the survey frequency relative error t change in time of the method for frequency power signal.

The present invention is based on phase-modulation to detect in the method for frequency power signal, described default sample frequency is 10kHz, input signal time 0.2s, signal frequency 50Hz, survey frequency relative error err<| ± 3| × 10 ^-7.As shown in Figure 4 be survey frequency relative error err (t) in time t change experimental result diagram.

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. detect a method for frequency power signal based on 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 correction reference frequency;

Described input signal sequence and described input signal 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 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;

Obtain the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence;

According to the frequency inverted rule preset, described phase differential and described correction reference frequency are converted to the frequency of described electric power signal.

2. the method detecting frequency power signal based on phase-modulation according to claim 1, it is characterized in that, 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 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.

3. the method detecting frequency power signal based on phase-modulation according to claim 2, it is characterized in that, according to the second transformation rule preset, described 1 π sequence length and described default sample frequency are converted to the step revising reference frequency and comprise 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 correction reference frequency.

4. the method detecting frequency power signal based on phase-modulation according to claim 1, it is characterized in that, the step obtaining the phase differential of the phase place of described first phase modulation sequence and the phase place of described second phase modulation sequence comprises the following steps:

Plural integral and calculating is carried out to described first phase modulation sequence, generates first phase;

Plural integral and calculating is carried out to described second phase modulation sequence, generates second phase;

Obtain the difference of described first phase and described second phase, generate described phase differential.

5. the method detecting frequency power signal 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 that described phase differential and described correction reference frequency are converted to the frequency of described electric power signal is comprised the following steps:

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

Described phase place ratio is multiplied with described correction reference frequency, generates the frequency of described electric power signal.

6. detect a system for frequency power signal based on 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;

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

Reference frequency correcting module, for according to the second transformation rule preset, is converted to correction reference 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 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 is transferred to another post module, for described input signal sequence and described input signal 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;

Phase difference module, for the phase differential of the phase place of the phase place and described second phase modulation sequence that obtain described first phase modulation sequence;

Frequency measuring block, for according to the frequency inverted rule preset, is converted to the frequency of described electric power signal by described phase differential and described correction reference frequency.

7. according to claim 6ly detect the system of frequency power signal based on phase-modulation, it is characterized in that, described 1 π sequence length module also 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.

8. according to claim 7ly detect the system of frequency power signal based on phase-modulation, it is characterized in that, described reference frequency correcting module also for:

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

The product obtaining described ratio and π is described correction reference frequency.

9. according to claim 6ly detect the system of frequency power signal based on phase-modulation, it is characterized in that, described phase difference module also for:

Plural integral and calculating is carried out to described first phase modulation sequence, generates first phase;

Plural integral and calculating is carried out to described second phase modulation sequence, generates second phase;

Obtain the difference of described first phase and described second phase, generate described phase differential.

10., according to detecting the system of frequency power signal based on phase-modulation in claim 6 to 9 described in any one, it is characterized in that, described frequency measuring block also for:

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

Described phase place ratio is multiplied with described correction reference frequency, generates the frequency of described electric power signal.