CN105656044A - FFT (Fast Fourier Transform) based current harmonic wave inhibition method - Google Patents
FFT (Fast Fourier Transform) based current harmonic wave inhibition method Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention relates to an FFT based current harmonic wave inhibition method, and belongs to the technical field of harmonic wave detection of the electrical network. Any subharmonic wave is extracted, the sum of the subharmonic components that satisfy the conditions extracted, when the load harmonic current exceeds the compensation capacity of an APF, only the characteristic subharmonic wave of high damage is compensated selectively, IFFT is carried out on the harmonic waves that satisfy the condition, and the sum of content of part of the harmonic waves is extracted. Thus, the method can be used in cooperation with a passive filter, and the APF only compensate required harmonic waves.
Description
Technical field
The invention belongs to Harmonic Detection technical field, it relates to a kind of method of suppression current harmonics based on fast Flourier conversion.
Background technology
Aviation AC power is transformed into direct current by AC/DC full bridge rectifier usually, supplies the high power density DC/DC switch power supply of various topology. With weaponry demand, more and more power electronic equipments injects harmonic wave in a large number to electrical network so that aviation ac power supply system electric current non-sinusoidal, or electric current be sinusoidal but with electrical network voltage not homophase. This can cause the problems such as energy transmission efficiency reduces, and electrical equipment is overheated. Harmonic problem is all paid close attention to by countries in the world fully, has held repeatedly academic conference about harmonic problem in the world, and many countries and international systematic learning organization have formulated standard and the regulation of restriction power system and electrical equipment harmonic wave. Consequently, it is desirable to airplane power source harmonic wave is studied and is controlled, it is to increase power grid quality, it is ensured that device security, reliability service.
At present, important measures of harmonics restraint adopt active power filtering device (APF). Active power filtering device is as electrical network system harmonics dynamic compensating device, and harmonic detecting is the basic demand that harmonic wave compensates. Existing harmonic detecting method mainly contains: band leads to or band resistance analog filter detection method, based on the detection method of instantaneous reactive power theory, and Wavelet Transform etc. Analog filter detection method mid-frequency is very responsive etc. to component parameters, and design is difficult, and error is big; Detection method based on instantaneous reactive power theory has now comprised method, method and method, and what these methods detected is each harmonic sum, cannot obtain each harmonic amplitude and phase place information.
Summary of the invention
The technical problem that the present invention solves is: a kind of method providing suppression current harmonics based on fast Flourier conversion.
The technical scheme of the present invention is: described detection method comprises the steps:
Step one, the D/A converter of signal processing device with sample frequency sampling electric current signal, simulating signal is changed into numeral sequence be stored in RAM;
Step 2, the capture-port of signal processing device catches the square wave positive rise that voltage zero-crossing detection circuit generates, and the sampling current data sequence preserved is carried out N point fft analysis, obtains discrete sequence of complex numbers X [0], an X [1] ... X [];
Step 3, asks for sequence of complex numbers X [0], X [1] ... power spectrum line A [1] of X [] correspondence, A [2] ... the amplitude of A [];
Step 4, search power spectrum wire spoke value, the frequency spectrum that power spectrum wire spoke value is less than condition carries out inverse-Fourier transform, obtains power spectrum wire spoke value and is less than the harmonic component sum defining value;
Step 5, using the harmonic component sum that obtains as the instruction suppressing current harmonics.
Harmonic current compensation instruction and actual offset current obtain the actuate signal of the power tube of PWM converter through current follow-up control circuit, ensure offset current tracing compensation instruction
Offset current generation circuit injects offset current to electrical network, and this electric current and harmonic wave are cancelled out each other, and mains by harmonics is inhibited.
The useful effect of the present invention: the technical program can extract any subharmonic and each harmonic component sum satisfied condition, when load harmonic current exceeds the compensation capacity of APF, it is possible to select only to compensate wherein to endanger bigger harmonics; The harmonic wave that satisfies condition can be implemented inverse-Fourier transform (IFFT), then extract this part harmonic wave content sum, with facilitate with passive filter with the use of occasion, APF only compensates required harmonic wave.
Accompanying drawing explanation
Fig. 1 is the FB(flow block) of the technical program;
Fig. 2 is radar equipment feeding load current typical waveform;
Fig. 3 is the total harmonic wave forms of load current;
Fig. 4 is for compensating rear supply current waveform;
Fig. 5 is total harmonic wave forms that amplitude is less than A [3]=1677.9;
Fig. 6 is that amplitude is less than the rear supply current of A [3]=1677.9 harmonic wave compensation.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described further as embodiment.
For each harmonic this demand of component sum that extraction satisfies condition; a kind of aircraft AC power harmonic detecting method based on Fast Fourier Transform (FFT) that this practicality invention proposes; but it is not as limiting to the invention; embodiment is only for illustrating the principle of the present invention; the present invention also has various improvement, and these improvement all fall in protection domain of the present invention. This example illustrates its implementation process by Matlab simulation software.
(1) rectifying circuit load current typical waveform is see Fig. 2;
(2) ac power frequency is f=400Hz;
(3) frequency f that load current is sampled by the A/D converter of dsp processor is determineds=50kHz;
(4) one-period sampling number
(5) FFT data computing length N=2 is got8=128;
(6) CAP unit inspection is to square wave signal edge;
(7) start the FFT that 125 sampling discrete data sequences are carried out N=128 by software, obtain Discrete Complex sequence X [1], X [2] ... X [128];
(8) calculated complex sequence power breadth of spectral line value A [1], A [2] ... A [128];
(9) searching for amplitude, the frequency spectrum that power spectrum wire spoke value is less than A [2]=8217.3 carries out inverse FFT conversion; Obtain harmonic component sum;
(10) result after proportional and integral controller of the instruction of harmonic component sum and actual offset current, through digital signal processor PWM module triangular modulation, generates compensating circuit actuate signal, completes harmonic wave compensation;
(12) the supply current waveform after compensating is see Fig. 4, and supply current waveform sine is better, and relatively load current is lower for harmonic wave content.
(13) searching for amplitude, the frequency spectrum that power spectrum wire spoke value is less than A [3]=1677.9 carries out inverse-Fourier transform (IFFT); Obtain harmonic component sum and see Fig. 5;
(14) result after proportional and integral controller of the instruction of harmonic component sum and actual offset current, through digital signal processor PWM module triangular modulation, generates compensating circuit actuate signal, completes harmonic wave compensation;
(15) the supply current waveform after compensating is see Fig. 6, and supply current waveform sine is better, and relatively load current is lower for harmonic wave content.
Claims (1)
1. a method for the suppression current harmonics converted based on fast Flourier, is characterized by: described detection method comprises the steps:
Step one, simulating signal, with the sample frequency sampling electric current signal of fs, is changed into numeral sequence and is stored in RAM by the D/A converter of signal processing device;
Step 2, the capture-port of signal processing device catches the square wave positive rise that voltage zero-crossing detection circuit generates, and the sampling current data sequence preserved is carried out N point fft analysis, obtain N/2 discrete sequence of complex numbers X [0], X [1] ... X [N/2];
Step 3, asks for sequence of complex numbers X [0], X [1] ... power spectrum line A [1] of X [N/2] correspondence, A [2] ... the amplitude of A [N/2];
Step 4, search power spectrum wire spoke value, the frequency spectrum that power spectrum wire spoke value is less than condition carries out inverse-Fourier transform, obtains power spectrum wire spoke value and is less than the harmonic component sum defining value;
Step 5, using the harmonic component sum that obtains as the instruction suppressing current harmonics;
Step 6, harmonic current compensation instruction and actual offset current obtain the actuate signal of the power tube of PWM converter through current follow-up control circuit, and offset current generation circuit injects offset current to electrical network.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105762798A (en) * | 2014-12-17 | 2016-07-13 | 中国航空工业集团公司雷华电子技术研究所 | Method for inhibiting current harmonics based on FFT (Fast Fourier Transform) |
| CN108471314A (en) * | 2018-02-24 | 2018-08-31 | 南方电网调峰调频发电有限公司 | A kind of Wave data compression method based on FFT transform |
| CN111812404A (en) * | 2020-09-14 | 2020-10-23 | 湖南国科雷电子科技有限公司 | Signal processing method and processing device |
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|---|---|---|---|---|
| CN1049058A (en) * | 1989-07-22 | 1991-02-06 | 云南省电力工业局试验研究所 | On-line overvoltage monitor for electric power system |
| CN1153556A (en) * | 1994-08-25 | 1997-07-02 | 西门子公司 | Method and device for monitoring a power supply network |
| CN101119136A (en) * | 2006-08-04 | 2008-02-06 | 华为技术有限公司 | A method and device for obtaining basic line parameters |
| CN101458291A (en) * | 2009-01-09 | 2009-06-17 | 南京因泰莱配电自动化设备有限公司 | Transformer partial discharge online detection data acquisition unit and detecting method |
| JP4766005B2 (en) * | 2007-06-07 | 2011-09-07 | 株式会社明電舎 | Harmonic current compensator |
| CN104065091A (en) * | 2014-07-02 | 2014-09-24 | 国家电网公司 | Static Var Generator with full APF function |
-
2014
- 2014-12-03 CN CN201410728163.1A patent/CN105656044B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1049058A (en) * | 1989-07-22 | 1991-02-06 | 云南省电力工业局试验研究所 | On-line overvoltage monitor for electric power system |
| CN1153556A (en) * | 1994-08-25 | 1997-07-02 | 西门子公司 | Method and device for monitoring a power supply network |
| CN101119136A (en) * | 2006-08-04 | 2008-02-06 | 华为技术有限公司 | A method and device for obtaining basic line parameters |
| JP4766005B2 (en) * | 2007-06-07 | 2011-09-07 | 株式会社明電舎 | Harmonic current compensator |
| CN101458291A (en) * | 2009-01-09 | 2009-06-17 | 南京因泰莱配电自动化设备有限公司 | Transformer partial discharge online detection data acquisition unit and detecting method |
| CN104065091A (en) * | 2014-07-02 | 2014-09-24 | 国家电网公司 | Static Var Generator with full APF function |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105762798A (en) * | 2014-12-17 | 2016-07-13 | 中国航空工业集团公司雷华电子技术研究所 | Method for inhibiting current harmonics based on FFT (Fast Fourier Transform) |
| CN108471314A (en) * | 2018-02-24 | 2018-08-31 | 南方电网调峰调频发电有限公司 | A kind of Wave data compression method based on FFT transform |
| CN111812404A (en) * | 2020-09-14 | 2020-10-23 | 湖南国科雷电子科技有限公司 | Signal processing method and processing device |
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