CN104502701B - Method and system based on phase-modulation detection frequency power signal - Google Patents
Method and system based on phase-modulation detection frequency power signal Download PDFInfo
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Abstract
The invention discloses a kind of method and system based on phase-modulation detection frequency power signal, methods described includes：According to preset signals time span and preset sample frequency, electric power signal is sampled, obtains input signal sequence；Measure the frequency of the input signal sequence, obtain the preliminary frequency of the electric power signal, and ± 1 π phase shift sequences of input signal sequence and input signal sequence are subtracted each other using the preliminary frequency as reference frequency, obtain two phase modulation sequences that phase changes with frequency input signal；Described two phase modulation sequences are used for frequency measurement.Implement the present invention, the frequency measurement of degree of precision can be obtained.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of electric power, in particular to a method and a system for detecting electric power signal frequency based on phase modulation.
[ background ] A method for producing a semiconductor device
The power frequency measurement has important significance on a power system, and the power grid has the operation rated power frequency of 50Hz and belongs to lower frequency. The frequency of the low-frequency signal can be measured according to the phase difference, and the basic principle is that 2 data sequences separated at intervals are taken, and the frequency is measured according to the phase difference of the 2 data sequences.
However, the actual power signal has subharmonic and subharmonic interference, and the 2-segment data sequence does not have the filter characteristic of the frequency domain, so that the subharmonic and subharmonic interference cannot be suppressed or attenuated, and the frequency measurement accuracy is reduced.
[ summary of the invention ]
In view of the above, it is necessary to provide a method and a system for detecting a frequency of an electric power signal based on phase modulation, which aims at the problem of low frequency measurement accuracy of the frequency measurement method.
A method for detecting a frequency of a power signal based on phase modulation, comprising the steps of:
sampling the power signal according to the preset signal time length and the preset sampling frequency to obtain an input signal sequence;
carrying out frequency initial measurement on the input signal sequence to generate an initial frequency of the power signal;
giving a reference frequency by the preliminary frequency, converting the preset sampling frequency into a sampling interval integer of the reference frequency at 1 pi phase shift according to a preset first conversion rule, and generating a 1 pi sequence length;
converting the length of the 1 pi sequence and the preset sampling frequency into a modified reference frequency according to a preset second conversion rule;
subtracting the phase shift sequence of the input signal at the length of the 1 pi sequence from the input signal sequence to generate a first phase modulation sequence with the phase varying with the frequency of the input signal;
subtracting the phase shift sequence of the input signal at the length of-1 pi sequence from the input signal sequence to generate a second phase modulation sequence with the phase varying with the frequency of the input signal;
acquiring a phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence;
and converting the phase difference and the correction reference frequency into the frequency of the electric power signal according to a preset frequency conversion rule.
A system for detecting a frequency of a power signal based on phase modulation, comprising:
the sampling module is used for sampling the electric power signal according to the preset signal time length and the preset sampling frequency to obtain an input signal sequence;
the preliminary frequency module is used for carrying out preliminary frequency measurement on the input signal sequence to generate a preliminary frequency of the electric power signal;
a 1 pi sequence length module, configured to give a reference frequency according to the preliminary frequency, convert the preset sampling frequency into a sampling interval integer of the reference frequency at 1 pi phase shift according to a preset first conversion rule, and generate a 1 pi sequence length;
the reference frequency correction module is used for converting the length of the 1 pi sequence and the preset sampling frequency into a corrected reference frequency according to a preset second conversion rule;
the first phase modulation module is used for subtracting the phase shift sequence of the input signal at the length of the 1 pi sequence from the input signal sequence to generate a first phase modulation sequence with the phase varying with the frequency of the input signal;
the second phase modulation module is used for subtracting the phase shift sequence of the input signal in the-1 pi sequence length from the input signal sequence to generate a second phase modulation sequence with the phase varying with the frequency of the input signal;
a phase difference module, configured to obtain a phase difference between a phase of the first phase modulation sequence and a phase of the second phase modulation sequence;
and the frequency measurement module is used for converting the phase difference and the correction reference frequency into the frequency of the electric power signal according to a preset frequency conversion rule.
According to the method and the system for detecting the frequency of the power signal based on the phase modulation, the sampling interval integer corresponding to the 1 pi phase shift is calculated according to the reference frequency and is the length of the 1 pi sequence, the corrected reference frequency is obtained according to the length of the 1 pi sequence, the input signal sequence and the phase shift sequence of the input signal in the length of the +/-1 pi sequence are subtracted to generate a first phase modulation sequence and a second phase modulation sequence of which the phases change along with the frequency of the input signal, noise or attenuation subharmonic and subharmonic interference can be effectively inhibited, the two phase modulation sequences are used for frequency measurement, and a frequency measurement result with higher precision can be obtained.
[ description of the drawings ]
FIG. 1 is a schematic flow chart of a first embodiment of a method for detecting a frequency of an electric power signal based on phase modulation according to the present invention;
fig. 2 is a schematic diagram of amplitude-frequency characteristics of a phase modulation sequence in the method for detecting the frequency of the power signal based on phase modulation according to the present invention;
FIG. 3 is a schematic diagram of a first embodiment of a system for detecting a frequency of an electrical power signal based on phase modulation according to the present invention;
fig. 4 is a schematic diagram of an experimental result of the variation of the measurement frequency relative error with time t according to the method for detecting the power signal frequency based on phase modulation.
[ detailed description ] embodiments
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
Although the steps in the present invention are shown and described using reference numbers, the order of the steps is not limited to any order, and the order of steps may be modified unless otherwise indicated or unless the order of steps or performance of certain steps requires otherwise.
Referring to fig. 1, fig. 1 is a flowchart illustrating a method for detecting a frequency of an electrical power signal based on phase modulation according to a first embodiment of the present invention.
The method for detecting the frequency of the power signal based on the phase modulation of the embodiment may include the following steps:
step S101, sampling the power signal according to a preset signal time length and a preset sampling frequency to obtain an input signal sequence.
And step S102, carrying out frequency initial measurement on the input signal sequence to generate an initial frequency of the power signal.
Step S103, a reference frequency is given by the preliminary frequency, the preset sampling frequency is converted into a sampling interval integer of the reference frequency at 1 pi phase shift according to a preset first conversion rule, and the length of the 1 pi sequence is generated.
And step S104, converting the length of the 1 pi sequence and the preset sampling frequency into a correction reference frequency according to a preset second conversion rule.
And S105, subtracting the phase shift sequence of the input signal in the length of the 1 pi sequence from the input signal sequence to generate a first phase modulation sequence with the phase varying with the frequency of the input signal.
And S106, subtracting the phase shift sequence of the input signal in the-1 pi sequence length from the input signal sequence to generate a second phase modulation sequence with the phase varying with the frequency of the input signal.
Step S107, a phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence is obtained.
Step S108, converting the phase difference and the corrected reference frequency into a frequency of the power signal according to a preset frequency conversion rule.
In this embodiment, the sampling interval integer corresponding to the 1 pi phase shift is calculated according to a reference frequency, which is the length of the 1 pi sequence, and the corrected reference frequency is obtained according to the length of the 1 pi sequence, and the input signal sequence and the phase shift sequence of the input signal at the length of the ± 1 pi sequence are subtracted to generate a first phase modulation sequence and a second phase modulation sequence, the phases of which change with the frequency of the input signal, so that the interference of noise or attenuation subharmonic and subharmonic can be effectively suppressed, and the two phase modulation sequences are used for frequency measurement, so that a frequency measurement result with higher precision can be obtained.
In step S101, the power signal may be sampled by a sampling device in the field of power grid, so as to obtain an input signal sequence.
Preferably, in order to ensure a certain frequency measurement real-time performance, the power system frequency generally refers to the average frequency of the signal in a time length of 0.2s, and the time length is preferably equal to 0.2s.
Further, the rated frequency of the power system is 50Hz, and for improving the performance, the sampling frequency should be much higher than 50Hz, and preferably, the sampling frequency is set to be equal to f n =10KHz, the sampling interval is expressed as formula (1):
in the formula, T n Is the sampling interval, in units of s; f. of n The preset sampling frequency is in Hz.
The sample input signal sequence length is expressed as formula (2):
N＝T s f n (2)；
wherein N is the input signal sequence length, the unit is dimensionless, T s Is the input time, unit s, corresponding to the input signal.
The input signal sequence is expressed by formula (3):
n＝-N π +1,-N π +2,....,-1,0,1,2,.....,N-N π -1 (3)；
in the formula, X i (n) is an input signal sequence; a is the signal amplitude in v; omega is signal frequency, unit rad/s; t is n Is the sampling interval, in units of s; n is a discrete number of sequences, and the unit is dimensionless; n is a radical of π Is 1 pi sequence length;is the initial phase, in units rad.
For step S102, a frequency preliminary measurement may be performed on the input signal sequence by a zero-crossing method, so as to obtain the preliminary frequency. The initial frequency measurement of the input signal sequence can also be performed by other frequency measurement methods customary to those skilled in the art.
The initial frequency is expressed as formula (4):
ω o (4)；
in the formula, omega o Is the preliminary frequency, in units rad/s;
for step S103, the frequency of the input signal sequence is tracked with the preliminary frequency as a reference frequency.
Preferably, the reference frequency is expressed by formula (5):
ω s ＝ω o (5)；
in the formula, ω s For reference frequency, in units rad/s; omega o For preliminary frequencies, the unit rad/s.
In one embodiment, the step of converting the preset sampling frequency into a sampling interval integer of the reference frequency shifted by 1 pi according to a preset first conversion rule, and generating the length of the 1 pi sequence may include the steps of:
and acquiring the ratio of the preset sampling frequency to the reference frequency.
And rounding down the product of the ratio and the pi to be the nearest integer to generate the length of the 1 pi sequence.
Further, converting the preset sampling frequency into a sampling interval integer of the reference frequency at 1 pi phase shift according to the preset first conversion rule formula (6), and generating a 1 pi sequence length: :
in the formula, N π Is the length of the 1 pi sequence, and the unit is dimensionless; omega s For reference frequency, in units rad/s; f. of n The preset sampling frequency is in Hz.
For step S104, the preset second conversion rule converts the length of the 1 pi sequence into the modified reference frequency for modifying N π The integer quantization has an error within 1 sampling interval.
In one embodiment, the step of converting the 1 pi sequence length and the preset sampling frequency into a modified reference frequency according to a preset second conversion rule may include the steps of:
acquiring the ratio of the preset sampling frequency to the length of the 1 pi sequence;
and acquiring the product of the ratio and the pi as the corrected reference frequency.
Preferably, the 1 pi sequence length can be converted into the modified reference frequency by the preset second conversion rule formula (7):
in the formula, ω set For the modified reference frequency, in units rad/s; n is a radical of π Is the length of the 1 pi sequence, and the unit is dimensionless; f. of n The preset sampling frequency is in Hz.
For step S105, the input signal sequence is subtracted from the phase shift sequence of the input signal at the length of the 1 pi sequence to generate a first phase modulation sequence whose phase varies with the frequency of the input signal.
Preferably, the first phase modulation sequence is formula (8):
in the formula, X Ph1 (n) is the first phase modulation sequence.
The first phase of the first phase modulation sequence is equation (9):
further, the amplitude-frequency characteristic of the first phase modulation sequence is shown in fig. 2. Wherein the signal frequency is 100 pi rad/s, the phase modulation sequence has better inhibiting effect on even subharmonics and has better attenuation effect on the subharmonics.
For step S106, the length of the-1 π sequence is the inverse of the length of the 1 π sequence.
Preferably, the second phase modulation sequence is represented by formula (10):
in the formula, X Ph2 (n) is the second phase modulation sequence.
The second phase of the second phase modulation sequence is of equation (11):
further, the amplitude-frequency characteristic of the second phase modulation sequence is shown in fig. 2. Wherein the signal frequency is 100 pi rad/s, the phase modulation sequence has better inhibiting effect on even subharmonics and has better attenuation effect on the subharmonics.
In step S107, the phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence may be obtained by a phase obtaining method that is commonly used in the power grid field.
In one embodiment, the step of obtaining the phase difference of the phase of the first phase modulation sequence and the phase of the second phase modulation sequence may comprise the steps of:
and performing complex integral calculation on the first phase modulation sequence to generate a first phase.
And carrying out complex integral calculation on the second phase modulation sequence to generate a second phase.
And acquiring a difference value of the first phase and the second phase to generate the phase difference.
Preferably, the phase difference is formula (12):
in the formula, pH 2 Is the second phase, unit rad; PH value 1 Is the first phase, in units rad; ph is 2 Is the second phase modulation phase, in units rad; ph is 1 Modulating the phase for the first phase, in units rad; Δ PH the phase difference, in units rad.
For step S108, the phase difference and the modified reference frequency may be converted into a frequency of the power signal by a frequency detection device in the field of power grid.
In one embodiment, the step of converting the phase difference and the modified reference frequency into the frequency of the power signal according to a preset frequency conversion rule may include the steps of:
and acquiring the ratio of the phase difference to pi to generate a phase position.
And multiplying the phase ratio value by the corrected reference frequency to generate the frequency of the power signal.
Preferably, the frequency of the power signal may be obtained according to the preset frequency conversion rule formula (13):
where ω is the frequency of the input signal sequence, in units rad/s; omega set For the modified reference frequency, in units rad/s.
In other embodiments, the phase of the phase modulation sequence may also be obtained by a complex integration method, which is familiar to those skilled in the art.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a system for detecting a frequency of an electrical power signal based on phase modulation according to a first embodiment of the present invention.
The system for detecting the power signal frequency based on the phase modulation of the present embodiment may include a sampling module 1010, a preliminary frequency measurement module 1020, a 1 pi sequence length module 1030, a reference frequency correction module 1040, a first phase modulation module 1050, a second phase modulation module 1060, a phase difference module 1070, and a frequency measurement module 1080, wherein:
the sampling module 1010 is configured to sample the power signal according to a preset signal time length and a preset sampling frequency, so as to obtain an input signal sequence.
A preliminary frequency module 1020, configured to perform preliminary frequency measurement on the input signal sequence, and generate a preliminary frequency of the power signal.
A 1 pi sequence length module 1030, configured to give a reference frequency according to the preliminary frequency, convert the preset sampling frequency into a sampling interval integer of the reference frequency at 1 pi phase shift according to a preset first conversion rule, and generate a 1 pi sequence length.
The reference frequency modification module 1040 is configured to convert the length of the 1 pi sequence and the preset sampling frequency into a modified reference frequency according to a preset second conversion rule.
And the first phase modulation module 1050 is configured to subtract the input signal sequence from the phase shift sequence of the input signal at the length of the 1 pi sequence, and generate a first phase modulation sequence with a phase varying with the frequency of the input signal.
And a second phase modulation module 1060, configured to subtract the sequence of the input signal from a phase-shifted sequence of the input signal at a sequence length of-1 pi, and generate a second phase modulation sequence with a phase varying with the frequency of the input signal.
A phase difference module 1070 is configured to obtain a phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence.
A frequency measurement module 1080, configured to convert the phase difference and the modified reference frequency into a frequency of the power signal according to a preset frequency conversion rule.
In this embodiment, the sampling interval integer corresponding to the 1 pi phase shift is calculated according to a reference frequency, and is a 1 pi sequence length, the corrected reference frequency is obtained according to the 1 pi sequence length, the input signal sequence and the phase shift sequence of the input signal in the sequence length of ± 1 pi are subtracted to generate a first phase modulation sequence and a second phase modulation sequence, the phases of which change with the frequency of the input signal, so that the interference of noise or attenuation subharmonic and subharmonic can be effectively suppressed, and the two phase modulation sequences are used for frequency measurement, so that a frequency measurement result with higher precision can be obtained.
For the sampling module 1010, the power signal may be sampled by a sampling device in the field of power grid, so as to obtain an input signal sequence.
Preferably, in order to ensure a certain frequency measurement real-time performance, the power system frequency generally refers to the average frequency of the signal in a time length of 0.2s, and the time length is preferably equal to 0.2s.
Further, the power system is ratedThe frequency is 50Hz, the sampling frequency is much higher than 50Hz for improving the performance, and the sampling frequency is preferably set to be equal to f n =10KHz, the sampling interval is expressed as formula (1):
in the formula, T n Is the sampling interval, in units of s; f. of n The preset sampling frequency is in Hz.
The sample input signal sequence length is expressed as formula (2):
N＝T s f n (2)；
wherein N is the input signal sequence length, the unit is dimensionless, T s Is the input time, unit s, corresponding to the input signal.
The input signal sequence is expressed by formula (3):
n＝-N π +1,-N π +2,....,-1,0,1,2,.....,N-N π -1 (3)；
in the formula, X i (n) is an input signal sequence; a is the signal amplitude in v; omega is signal frequency, unit rad/s; t is a unit of n Is the sampling interval, in units of s; n is a discrete number of sequences, and the unit is dimensionless; n is a radical of π Is 1 pi sequence length;is the initial phase, in units rad.
For the preliminary frequency measurement module 1020, the preliminary frequency may be obtained by performing a preliminary frequency measurement on the input signal sequence through a zero-crossing method. The initial frequency measurement of the input signal sequence can also be performed by other frequency measurement methods customary to those skilled in the art.
Preferably, the initial frequency is expressed by formula (4):
ω o (4)；
in the formula, ω o Is the initial frequency, unit rad/s;
for the 1 pi sequence length module 1030, the frequency of the input signal sequence is tracked with the preliminary frequency as a reference frequency. The preset sampling frequency can be converted into a sampling interval number integer corresponding to 1 pi phase shift through sampling interval detection equipment in the field of power grids.
Preferably, the reference frequency is expressed by formula (5):
ω s ＝ω o (5)；
in the formula, ω s For reference frequency, in units rad/s; omega o For preliminary frequencies, the unit rad/s.
In one embodiment, the 1 π sequence length module 1030 is also operable to:
and acquiring the ratio of the preset sampling frequency to the reference frequency.
And rounding down the product of the ratio and the pi into the nearest integer to generate the length of the 1 pi sequence.
Further, converting the preset sampling frequency into a sampling interval integer of the reference frequency shifted at 1 pi according to the preset first conversion rule formula (6), and generating the length of the 1 pi sequence: :
in the formula, N π Is the length of the 1 pi sequence, and the unit is dimensionless; omega s For reference frequency, in units rad/s; f. of n The preset sampling frequency is in Hz.
For the reference frequency modification module 1040, the preset second conversion rule converts the length of the 1 pi sequence into the modified reference frequency for modifying N π The integer quantization has an error within 1 sampling interval.
In one embodiment, the reference frequency correction module 1040 is further operable to:
and acquiring the ratio of the preset sampling frequency to the length of the 1 pi sequence.
And acquiring the product of the ratio and the pi as the corrected reference frequency.
Preferably, the 1 pi sequence length can be converted into the modified reference frequency by the preset second conversion rule formula (7):
in the formula, ω set For the modified reference frequency, in units rad/s; n is a radical of hydrogen π Is the length of the 1 pi sequence, and the unit is dimensionless; f. of n The preset sampling frequency is in Hz.
For the first phase modulation module 1050, the input signal sequence is subtracted from the phase shift sequence of the input signal at the length of the 1 pi sequence to generate a first phase modulation sequence with a phase varying with the frequency of the input signal.
Preferably, the first phase modulation sequence is formula (8):
in the formula, X Ph1 (n) is the first phase modulation sequence.
The phase of the first phase modulation sequence is of formula (9):
further, the amplitude-frequency characteristic of the first phase modulation sequence is shown in fig. 2. Wherein, the signal frequency is 100 pi rad/s, the phase modulation sequence has better inhibiting effect on even subharmonics and has better attenuation effect on the subharmonics.
For the second phase modulation block 1060, the-1 pi sequence length is the inverse of the 1 pi sequence length.
Preferably, the second phase modulation sequence is represented by formula (10):
in the formula, X Ph2 (n) is the second phase modulation sequence.
The phase of the second phase modulation sequence is of formula (11):
further, the amplitude-frequency characteristic of the second phase modulation sequence is shown in fig. 2. Wherein, the signal frequency is 100 pi rad/s, the phase modulation sequence has better inhibiting effect on even subharmonics and has better attenuation effect on the subharmonics.
For the phase difference module 1070, the phase difference of the phase of the first phase modulation sequence and the phase of the second phase modulation sequence is obtained.
In one embodiment, the phase difference module 1070 may also be configured to:
and performing complex integral calculation on the first phase modulation sequence to generate a first phase.
And carrying out complex integral calculation on the second phase modulation sequence to generate a second phase.
And acquiring a difference value of the first phase and the second phase to generate the phase difference.
Preferably, the phase difference may be obtained by the following equation (12):
in the formula, pH 2 Is the second phase, unit rad; PH value 1 Is the first phase, in units rad; ph 2 For said second phase modulation phase, unit rad；Ph 1 Is the first phase modulation phase, in units rad; Δ PH the phase difference, in units rad.
For the frequency measurement module 1080, the phase difference and the corrected reference frequency may be converted into the frequency of the power signal by a frequency detection device in the field of power grids.
In one embodiment, the frequency measurement module is further configured to:
and acquiring the ratio of the phase difference to pi to generate a phase position.
And multiplying the phase ratio value by the corrected reference frequency to generate the frequency of the power signal.
Preferably, the frequency measuring module 1080 may obtain the frequency of the power signal according to the preset frequency conversion rule (13):
where ω is the frequency of the input signal sequence, in units rad/s; omega set For the modified reference frequency, the unit rad/s.
In other embodiments, the phase of the phase modulation sequence may also be obtained using phase calculation methods familiar to those skilled in the art.
Referring to fig. 4, fig. 4 is a schematic diagram illustrating an experimental result of measuring a frequency relative error along with a time t according to the method for detecting a power signal frequency based on phase modulation of the present invention.
In the method for detecting the frequency of the power signal based on the phase modulation, the preset sampling frequency is 10kHz, the input signal time is 0.2s, the signal frequency is 50Hz, and the relative error err of the measured frequency<|±3|×10 -7 . Fig. 4 is a graph showing the experimental results of measuring the frequency versus error err (t) as a function of time t.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (4)
1. A method for detecting a frequency of an electrical power signal based on phase modulation, comprising the steps of:
sampling the power signal according to a preset signal time length and a preset sampling frequency to obtain an input signal sequence;
carrying out frequency initial measurement on the input signal sequence to generate an initial frequency of the power signal;
giving a reference frequency by the preliminary frequency, converting the preset sampling frequency into a sampling interval integer of the reference frequency at 1 pi phase shift according to a preset first conversion rule, and generating a 1 pi sequence length;
converting the length of the 1 pi sequence and the preset sampling frequency into a modified reference frequency according to a preset second conversion rule;
subtracting the phase shift sequence of the input signal sequence at the length of the 1 pi sequence from the input signal sequence to generate a first phase modulation sequence with the phase varying with the frequency of the input signal;
subtracting the phase shift sequence of the input signal sequence at the length of-1 pi sequence from the input signal sequence to generate a second phase modulation sequence with the phase varying with the frequency of the input signal;
acquiring a phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence;
converting the phase difference and the correction reference frequency into the frequency of the electric power signal according to a preset frequency conversion rule;
the preset first conversion rule is as follows:
wherein, N π Is the length of the 1 pi sequence, and the unit is dimensionless; omega s For reference frequency, in units rad/s; f. of n The preset sampling frequency is in Hz;
the preset second conversion rule is as follows:
wherein, ω is set For the modified reference frequency, in units rad/s;
the preset frequency conversion rule is as follows:
wherein ω is the frequency of the input signal sequence in units rad/s; omega set For the modified reference frequency, in units rad/s; Δ PH is the phase difference of the phase of the first phase modulation sequence and the phase of the second phase modulation sequence, in units rad.
2. The method for detecting the frequency of the power signal based on the phase modulation according to claim 1, wherein the step of obtaining the phase difference between the phase of the first phase modulation sequence and the phase of the second phase modulation sequence comprises the steps of:
performing complex integral calculation on the first phase modulation sequence to generate a first phase;
performing complex integral calculation on the second phase modulation sequence to generate a second phase;
and acquiring a difference value of the first phase and the second phase to generate the phase difference.
3. A system for detecting a frequency of an electrical power signal based on phase modulation, comprising:
the sampling module is used for sampling the electric power signal according to the preset signal time length and the preset sampling frequency to obtain an input signal sequence;
the preliminary frequency module is used for carrying out preliminary frequency measurement on the input signal sequence to generate a preliminary frequency of the electric power signal;
a 1 pi sequence length module, configured to give a reference frequency according to the preliminary frequency, convert the preset sampling frequency into a sampling interval integer with the reference frequency shifted by 1 pi according to a preset first conversion rule, and generate a 1 pi sequence length;
the reference frequency correction module is used for converting the length of the 1 pi sequence and the preset sampling frequency into a corrected reference frequency according to a preset second conversion rule;
the first phase modulation module is used for subtracting the phase shift sequence of the input signal sequence at the length of the 1 pi sequence from the input signal sequence to generate a first phase modulation sequence with the phase varying with the frequency of the input signal;
the second phase modulation module is used for subtracting the phase shift sequence of the input signal sequence at the length of-1 pi sequence from the input signal sequence to generate a second phase modulation sequence with the phase varying with the frequency of the input signal;
a phase difference module, configured to obtain a phase difference between a phase of the first phase modulation sequence and a phase of the second phase modulation sequence;
the frequency measurement module is used for converting the phase difference and the correction reference frequency into the frequency of the electric power signal according to a preset frequency conversion rule;
the preset first conversion rule is as follows:
wherein N is π Is the length of the 1 pi sequence, and the unit is dimensionless; omega s For reference frequency, in units rad/s; f. of n The preset sampling frequency is in Hz;
the preset second conversion rule is as follows:
wherein, ω is set For the modified reference frequency, in units rad/s;
the preset frequency conversion rule is as follows:
wherein ω is the frequency of the input signal sequence in units rad/s; omega set For the modified reference frequency, in units rad/s; Δ PH is the phase difference of the phase of the first phase modulation sequence and the phase of the second phase modulation sequence, in units rad.
4. The system for detecting a frequency of an electrical power signal based on phase modulation of claim 3, wherein the phase difference module is further configured to:
performing complex integral calculation on the first phase modulation sequence to generate a first phase;
performing complex integral calculation on the second phase modulation sequence to generate a second phase;
and acquiring a difference value of the first phase and the second phase to generate the phase difference.
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| CN105092967B (en) * | 2015-07-09 | 2018-03-20 | 广东电网有限责任公司电力科学研究院 | The frequency detecting method and system of electric power signal |
| CN105158558B (en) * | 2015-09-18 | 2018-04-03 | 广东电网有限责任公司电力科学研究院 | The frequency detecting method and system of electric power signal |
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| CN101057150A (en) * | 2004-09-13 | 2007-10-17 | 菲尔特罗尼克公开有限公司 | Method and apparatus for measuring the frequency of a received signal |
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