CN103592513B - Electric power signal harmonic analysis method and device - Google Patents
Electric power signal harmonic analysis method and device Download PDFInfo
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- CN103592513B CN103592513B CN201310580763.3A CN201310580763A CN103592513B CN 103592513 B CN103592513 B CN 103592513B CN 201310580763 A CN201310580763 A CN 201310580763A CN 103592513 B CN103592513 B CN 103592513B
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Abstract
Disclosure one electric power signal harmonic analysis method, including: (1) selects a phase voltage or electric current, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, again divided by amount of cycles, obtain the averaged count of power frequency component; (2) the counting step-length interval as the sampling period in sampling period is determined; (3) starting point of power frequency component is obtained by electric circuit inspection; And (4) take DFT mode to carry out Fourier transformation, only calculate amplitude and the phase angle of harmonic component interested.
Description
Technical field
The present invention relates to a kind of Power signal processing method, particularly to a kind of electric power signal harmonic analysis method and device.
Background technology
In prior art, electric power signal is carried out frequency analysis, generally have two ways: 1, PLL synchronous sampling circuit analysis; 2, windowed interpolation analysis.
Above two mode, is all by gathering synchronizing signal, or obtains a signal sequence by windowed interpolation, then carry out FFT, obtain each harmonic component.
Phaselocked loop requires electric power signal is synchronized, and wherein may relate to high frequency multiplication, which increases the degree of difficulty of circuit design.
FFT calculates all harmonic value, but actually only need to measure wherein fractional harmonic, virtually adds amount of calculation.
Power frequency component frequency can be accurately calculated and the little electric power signal harmonic analysis method of amount of calculation becomes urgent problem in the industry therefore it provides a kind of.
Summary of the invention
It is an object of the invention to provide a kind of electric power signal harmonic analysis method and device, it can accurately calculate power frequency component frequency and can effectively reduce amount of calculation.
According to the present invention, a kind of electric power signal harmonic analysis method is provided, including: (1) selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, then divided by amount of cycles, obtain the averaged count of power frequency component; (2) the counting step-length interval as the sampling period in sampling period is determined; (3) starting point of power frequency component is obtained by electric circuit inspection; And (4) take DFT mode to carry out Fourier transformation, only calculate amplitude and the phase angle of harmonic component interested.
Preferably, the present invention provides a kind of electric power signal harmonic analysis method, including: (1) selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, then divided by amount of cycles, obtain the averaged count of power frequency component; (2) the counting step-length interval as the sampling period in sampling period is determined;(3) zero crossing of sinusoidal wave ascent stage of power frequency component is obtained by electric circuit inspection as the starting point of power frequency component; And (4) take DFT mode to carry out Fourier transformation, only calculate amplitude and the phase angle of harmonic component interested.
More preferably, the present invention provides a kind of electric power signal harmonic analysis method, including: (1) selects a phase voltage, utilize high-frequency counting clock, zero crossing at power frequency component proceeds by counting, spends null cycle through several, obtains count value altogether, again divided by amount of cycles, obtain the averaged count of power frequency component; (2) the counting step-length interval as the sampling period in sampling period is determined; (3) zero crossing of sinusoidal wave ascent stage of power frequency component is obtained by electric circuit inspection as the starting point of power frequency component; And (4) take DFT mode to carry out Fourier transformation, only calculate amplitude and the phase angle of harmonic component interested.
Wherein, discrete Fourier transform (DiscreteFourierTransform is abbreviated as DFT) is Fourier transformation is all discrete form in time domain and frequency domain, is the frequency domain sample of its DTFT by the transform time domain samples of signal. In form, the sequence of conversion two ends (time domain and on frequency domain) is time-limited, and actually these two groups of sequences should be considered as all the main value sequence of Discrete Periodic Signals. Even if time-limited discrete signal is made DFT, it should also regarded as the conversion of its periodic extension. Fast Fourier transform is generally adopted to calculate DFT in actual applications.
Selectively, proceeding by counting from the starting point of ADC output, counting step is 2N starting point, and count value is S, and count frequency is fc, then the signal frequency tested is fc N/S.
Preferably, proceeding by counting from the zero crossing of ADC output, counting step is 2N zero crossing, and count value is S, and count frequency is fc, then the signal frequency tested is fc N/S.
Wherein, ADC, the abbreviation of Analog-to-DigitalConverter, refer to A/D converter or analog/digital converter. Refer to the device that the analogue signal of continuous variable is converted to discrete digital signal.
Preferably, the zero crossing at power frequency component proceeds by counting, spends null cycle through several, obtains count value altogether.
Selectively, set sample frequency as M times of power frequency, i.e. each cycle sampling M point, then with fc for count frequency, it is determined that sampling step length is S/N/M.
Selectively, M value range for 100��150.
Selectively, every cycle sampling M point, P cycle of sampling, obtains common M*P point sequence of real numbers altogether.
Selectively, P value range for 5��15.
Preferably, M value is 128, P values is 8, to 1024 obtained point sequences, takes DFT mode to carry out Fourier transformation, and formula is as follows:
Wherein, spectral resolution f0/ 8, the 8th of frequency spectrum, 16 ..., 8m component is first-harmonic respectively, second harmonic ..., m subharmonic;
Corresponding amplitude is
Phase angle isM=8,16 ..., 8i..., (i=1,2,3...).
Wherein, the amplitude calculated and phase angle are based on the relative value of first-harmonic.
The present invention also provides for a kind of electric power signal frequency analysis device, including: power frequency component averaged count acquisition device, power frequency component averaged count acquisition device selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, then divided by amount of cycles, obtain the averaged count of power frequency component; Sample period time spacer, sample period time spacer is using the counting step-length in sampling period as the interval in sampling period; Power frequency component starting point detecting device, power frequency component starting point detecting device obtains the starting point of power frequency component by electric circuit inspection; And computational analysis device, computational analysis device takes DFT mode to carry out Fourier transformation, only calculates amplitude and the phase angle of harmonic component interested.
Preferably, a kind of electric power signal frequency analysis device is provided, including: power frequency component averaged count acquisition device, power frequency component averaged count acquisition device selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, again divided by amount of cycles, obtain the averaged count of power frequency component; Sample period time spacer, sample period time spacer is using the counting step-length in sampling period as the interval in sampling period; Power frequency component starting point detecting device, power frequency component starting point detecting device obtains the zero crossing starting point as power frequency component of the sinusoidal wave ascent stage of power frequency component by electric circuit inspection; And computational analysis device, computational analysis device takes DFT mode to carry out Fourier transformation, only calculates amplitude and the phase angle of harmonic component interested.
Wherein, power frequency component averaged count acquisition device proceeds by counting from the ADC zero crossing exported, and counting step is 2N zero crossing, and count value is S, and count frequency is fc, then the signal frequency tested is fc N/S.
Wherein, sample period time spacer sets sample frequency as M times of power frequency, i.e. each cycle sampling M point, then with fc for count frequency, it is determined that sampling step length is S/N/M.
Wherein, computational analysis device sets every cycle sampling M point, and P cycle of sampling, obtains common M*P point sequence of real numbers altogether.
The invention has the beneficial effects as follows: (1) adopts unique sample-synchronous mode; (2) adopt DFT mode, only harmonic wave interested is calculated. Therefore, while ensureing accurately to calculate power frequency component frequency, amount of calculation is effectively reduced.
Detailed description of the invention
Disclosure one electric power signal harmonic analysis method and device, be characterized in adopting unique sample-synchronous mode, and adopt DFT mode only harmonic wave interested to be calculated.
The sampled point that frequency analysis uses, it is necessary to electric power signal with frequency homophase, namely synchronous sampling signal, first the present invention carries out frequency measurement, then starts sampling in cycle starting point, can meet above-mentioned requirements.
Measure the cycle of power frequency component, utilize high-frequency counting clock, zero crossing at power frequency component proceeds by counting, null cycle is spent, for instance in 100,1000 cycles, obtain count value altogether through multiple, again divided by amount of cycles, obtain the averaged count of a power frequency component, and counting clock is more accurately, thus can calculate the frequency obtaining power frequency component more accurately.
After determining work frequency, can obtaining the counting step-length in sampling period, this is the interval in sampling period.
In order to reach sampling with power frequency component with frequency homophase, it is thus necessary to determine that the starting point of power frequency component, with the zero crossing of sinusoidal wave ascent stage for starting point, this point can be by what electric circuit inspection arrived.
So, when starting point and time cycle are all determined, the signal sequence of needs can be collected.
Frequency analysis only has fractional harmonic to be valuable, and Fourier transformation analysis may produce multiple-harmonic result perhaps, such as 1024 FFT, this FFT can analyze 1024 harmonic value simultaneously, but only wherein tens be useful, such as 51, then remaining harmonic value is exactly unnecessary, and amount of calculation is very big.
Therefore, it is intended that calculate part interested by DFT, reduce amount of calculation with this.
A specific embodiments of this algorithm is presented herein below.
1. mains frequency is measured
Selecting a phase voltage to measure, proceed by counting from the zero crossing of ADC output, counting step is 2N zero crossing, and count value is S, and count frequency is fc, then the mains frequency tested is fc N/S.
2. the determination of sample frequency
Assume that sample frequency is power frequency 128 times, namely each cycle is sampled 128 points, then with fc for count frequency, it is determined that sampling or the step-length of the clock of extracted data is S/N/128.
3. the determination of sampling clock phase
For accomplishing that sampled data and civil power are with frequency homophase, it is thus necessary to determine that sampling output or the initial position of extracted data are positioned at the zero crossing of civil power.
4. the determination of sampling length
Every cycle is sampled 128 points, and 8 cycles of sampling, obtain totally 1024 sequence of real numbers altogether.
5. Harmonics Calculation
To 1024 obtained point sequences, take DFT mode to carry out Fourier transformation, only calculate amplitude and the phase angle of harmonic component interested.
The spectral resolution f of the Fourier transformation of this mode0/ 8, so the 8th of frequency spectrum the, 16 ..., 8m component is first-harmonic respectively, second harmonic ..., m subharmonic.
Corresponding amplitude is
Phase angle isM=8,16 ..., 8i..., (i=1,2,3...).
The present invention also provides for a kind of electric power signal frequency analysis device, comprising: power frequency component averaged count acquisition device, power frequency component averaged count acquisition device selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, again divided by amount of cycles, obtain the averaged count of power frequency component, power frequency component averaged count acquisition device proceeds by counting from the ADC zero crossing exported, counting step is 2N zero crossing, count value is S, count frequency is fc, the signal frequency then tested is fc N/S, sample period time spacer, sample period time spacer is using the counting step-length in sampling period as the interval in sampling period, sample period time spacer sets sample frequency as M times of power frequency, i.e. each cycle sampling M point, then with fc for count frequency, it is determined that sampling step length is S/N/M, power frequency component starting point detecting device, power frequency component starting point detecting device obtains the zero crossing starting point as power frequency component of the sinusoidal wave ascent stage of power frequency component by electric circuit inspection, and computational analysis device, computational analysis device takes DFT mode to carry out Fourier transformation, only calculates amplitude and the phase angle of harmonic component interested, and computational analysis device sets every cycle sampling M point, and P cycle of sampling, obtains common M*P point sequence of real numbers altogether.
Although the preferred embodiment of the present invention being described in detail at this, it is to be understood that the invention is not limited in the concrete structure being described in detail here and illustrating, may be effected by one skilled in the art other modification and variant when not necessarily departing from the spirit and scope of the invention.
Claims (10)
1. an electric power signal harmonic analysis method, it is characterised in that described method includes:
(1) select a phase voltage or electric current, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, then divided by amount of cycles, obtain the averaged count of power frequency component;
(2) the counting step-length interval as the sampling period in sampling period is determined;
(3) take DFT mode to carry out Fourier transformation, only calculate the amplitude of harmonic component interested;
(4) starting point of power frequency component is obtained by electric circuit inspection; And
(5) the described starting point obtained based on step (4), takes DFT mode to carry out Fourier transformation, only calculates the phase angle of harmonic component interested.
2. electric power signal harmonic analysis method as claimed in claim 1, it is characterised in that proceeding by counting from the starting point of ADC output, counting step is 2N starting point, and count value is S, and count frequency is fc, then the signal frequency tested is fc N/S.
3. electric power signal harmonic analysis method as claimed in claim 2, it is characterised in that sets sample frequency as M times of power frequency, namely each cycle is sampled M point, then with fc for count frequency, it is determined that sampling step length is S/N/M.
4. electric power signal harmonic analysis method as claimed in claim 3, it is characterised in that every cycle sampling M point, P cycle of sampling, obtains common M*P point sequence of real numbers altogether.
5. electric power signal harmonic analysis method as claimed in claim 4, it is characterised in that M value is 128, P values is 8, to 1024 obtained point sequences, takes DFT mode to carry out Fourier transformation, and formula is as follows:
Wherein, spectral resolution f0/8, the 8th of frequency spectrum, 16 ..., 8m component is first-harmonic respectively, second harmonic ..., m subharmonic;
Corresponding amplitude is
Phase angle isM=8,16 ..., 8i ..., (i=1,2,3 ...).
6. electric power signal harmonic analysis method as claimed in claim 5, it is characterised in that the amplitude calculated and phase angle are based on the relative value of first-harmonic.
7. an electric power signal frequency analysis device, it is characterised in that described device includes:
Power frequency component averaged count acquisition device, described power frequency component averaged count acquisition device selects a phase voltage, utilize high-frequency counting clock that power frequency component is counted, through several cycles, obtain count value altogether, again divided by amount of cycles, obtain the averaged count of power frequency component;
Sample period time spacer, described sample period time spacer is using the counting step-length in sampling period as the interval in sampling period;
Power frequency component starting point detecting device, described power frequency component starting point detecting device obtains the starting point of power frequency component by electric circuit inspection; And
Computational analysis device, described computational analysis device takes DFT mode to carry out Fourier transformation, only calculates the amplitude of harmonic component interested, and only calculates the phase angle of harmonic component interested based on the starting point of the power frequency component obtained.
8. electric power signal frequency analysis device as claimed in claim 7, it is characterized in that, described power frequency component averaged count acquisition device proceeds by counting from the ADC starting point exported, counting step is 2N starting point, count value is S, count frequency is fc, then the signal frequency tested is fc N/S.
9. electric power signal frequency analysis device as claimed in claim 8, it is characterised in that described sample period time spacer sets sample frequency as M times of power frequency, namely each cycle is sampled M point, then with fc for count frequency, it is determined that sampling step length is S/N/M.
10. electric power signal frequency analysis device as claimed in claim 9, it is characterised in that described computational analysis device sets every cycle sampling M point, and P cycle of sampling, obtains common M*P point sequence of real numbers altogether.
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| CN108362940B (en) * | 2018-03-14 | 2020-07-14 | 贵州电网有限责任公司 | Dynamic harmonic frequency extraction method of half-cycle distortion signal |
| CN113820539B (en) * | 2021-08-19 | 2024-05-28 | 南京国电南自电网自动化有限公司 | Harmonic wave and inter-harmonic wave angle calibration method and system based on fundamental wave angle calibration |
| CN114705913B (en) * | 2022-04-12 | 2024-01-09 | 上海赢双电机科技股份有限公司 | Harmonic analysis method of rotary transformer |
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