CN106771597B - A kind of no phase-locked loop formula SAI harmonic current detecting method omitting Park transformation - Google Patents
A kind of no phase-locked loop formula SAI harmonic current detecting method omitting Park transformation Download PDFInfo
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- CN106771597B CN106771597B CN201710124714.7A CN201710124714A CN106771597B CN 106771597 B CN106771597 B CN 106771597B CN 201710124714 A CN201710124714 A CN 201710124714A CN 106771597 B CN106771597 B CN 106771597B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
- G01R23/165—Spectrum analysis; Fourier analysis using filters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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Abstract
The invention discloses a kind of no phase-locked loop formula SAI harmonic current detecting methods of omission Park transformation, in traditional ip‑iqPark transformation and phase-locked loop are omitted on the basis of method and the low-pass filter in original system is substituted for sinusoidal magnitude value integrator, to enormously simplify the structure of system.Link is extracted with the fundamental positive sequence of SAI and substitutes LPF, under conditions of only extracting fundamental positive sequence, is carried out total current compensation, is improved the accuracy of harmonic current compensation.Whole system is because LPF link by SAI substitution, omission phase-locked loop and Park transform part, so that the rapidity of system response increases, forms a kind of accurate, quick and extremely easy Harmonic detection.This method has excellent performance in numerous Harmonic detections, there is boundless application prospect in active power filtering field.
Description
Technical field
The present invention relates to power inverter modulation control field, especially a kind of no phase-locked loop formula omitted under Park transformation
Harmonic currents detection method.
Background technique
The generally use of power electronic equipment and nonlinear load, makes harmonic current largely inject power grid, seriously affects electricity
The safe operation of net, therefore introduce Active Power Filter-APF (Active Power Filter-APF) and carry out harmonics restraint.Its
Basic principle is that harmonic wave is detected from target compensation, by compensation device generate one with the harmonic current is equal in magnitude and polarity
Opposite compensation electric current, so that the harmonic current in power grid be made to be filtered out.So the key link that APF carries out harmonics restraint is
The detection of harmonic current.
Current main Harmonic detection has: the detection method based on Fourier transformation is based on instantaneous reactive power theory
Detection method, detection method neural network based, be based on wavelet analysis detection method, the detection method based on filter
Deng, and the i on the basis of instantaneous reactive power theory is built upon using more extensive harmonic current detecting methodp-iqMethod, should
Method converts on the basis of application phaselocked loop by Clark and Park, fundamental current is obtained using low-pass filter, to mention
Take harmonic current.
Summary of the invention
Nothing that is simple, tracking accurate, fast response time omission Park transformation that it is an object of that present invention to provide a kind of structures
PLL SAI harmonic current detecting method.
To achieve the above object, use following technical scheme: steps are as follows for the method for the invention:
Step 1, simplifying ip-iqIn the case where method system structure, load-side three-phase current is extracted, is converted by Clark
Operation obtains the electric current under two-phase stationary coordinate system；
Step 2, the extraction of SAI link fundamental positive sequence is carried out to the electric current under two-phase stationary coordinate system；
Step 3, the operation of Clark inverse transformation is carried out to the fundamental positive sequence electric current extracted, obtains the fundamental positive sequence electricity of three-phase
Stream；
Step 4, harmonic current is extracted on the basis of three-phase fundamental positive sequence electric current.
Compared with prior art, the method for the present invention has the advantages that
1, Park transform part is eliminated, the structure of system is simplified and increases the accurate of system to a certain extent
Property.
2, the present invention is the detection method of no phase-locked loop, has simplified the structure of system, has increased the rapidity of system.
3, harmonic current is extracted and obtained to fundamental positive sequence electric current using SAI link, so that the extraction of harmonic current
More accurately and quickly.
Detailed description of the invention
Fig. 1 is overall structure block diagram of the present invention.
Fig. 2 is traditional ip-iqMethod structural block diagram.
Fig. 3 is the SAI schematic diagram of positive sequence.
Fig. 4 is the amplitude-frequency characteristic figure of fundamental positive sequence.
Fig. 5 is the SAI schematic diagram of negative phase-sequence.
Fig. 6 is the amplitude-frequency characteristic figure of fundamental wave negative sequence.
Fig. 7 is the SAI filter structure block diagram of fundamental frequency of the invention.
Fig. 8 is the acquisition figure of harmonic current of the invention.
Specific embodiment
The present invention will be further described with reference to the accompanying drawing:
Steps are as follows for the method for the invention:
Step 1, simplifying ip-iqIn the case where method system structure, load-side three-phase current is extracted, is converted by Clark
Operation obtains the electric current under two-phase stationary coordinate system；
Step 2, the extraction of SAI link fundamental positive sequence is carried out to the electric current under two-phase stationary coordinate system；
Step 3, the operation of Clark inverse transformation is carried out to the fundamental positive sequence electric current extracted, obtains the fundamental positive sequence electricity of three-phase
Stream；
Step 4, harmonic current is extracted on the basis of three-phase fundamental positive sequence electric current.
As shown in Figure 1, being the entire block diagram of system, threephase load electric current ia、ib、icUnder Clark transformation, two-phase is formed
Electric current i under rest frameα、iβ, fundamental positive sequence electric current i is extracted by SAI link+ α1、i+ β1, then pass through Clark contravariant
Get three-phase fundamental positive sequence electric current i in return+ α1、i+ b1、i+ c1, finally harmonic current i is obtained by operationaf、ibf、icf, to realize
Total current compensation.
Fig. 2 is traditional ip-iqThe structural block diagram of method, threephase load electric current ia、ib、icUnder Clark transformation, two-phase is formed
Electric current i under rest frameα、iβ, converted via the phase angle of phaselocked loop output voltage for Park, by low-pass filter pair
The transformed electric current i of Parkp、iqIt is filtered, obtains the DC component of the electric current under two-phase rotating coordinate systemThen
By Park, Clark inverse transformation, the fundamental current i of three-phase is formedaf、ibf、icf, finally obtain harmonic current i* ca、i* cb、i* cc.With
Fig. 1 is compared, and systematic comparison is complicated, is increased phaselocked loop and Park transform part, is made the accuracy of system to a certain extent
It reduces, and the use of low-pass filter plays time-lag action to system.For disadvantage mentioned above, the invention proposes a kind of provinces
The slightly no phase-locked loop formula SAI Harmonic currents detection method of Park transformation, enormously simplifies the structure of system, increases the quick of system
Property etc..
Fig. 3 is the SAI schematic diagram of positive sequence.Using the SAI extraction method of positive sequence, fundamental positive sequence is extracted, it can be with
The fundamental positive sequence electric current under the no phase-locked loop formula SAI Harmonic currents detection method for omitting Park transformation is obtained, is mentioned for harmonic current
It takes and lays a good foundation.
Fig. 4 is the amplitude-frequency characteristic figure of fundamental positive sequence.It can be seen that by the amplitude-frequency characteristic figure of fundamental positive sequence in center angular frequency
Place has resonance peak, all has attenuation for the signal of other frequencies, and the positive-sequence component of 50Hz is selected with polarity
Select effect.
Fig. 5 is the SAI schematic diagram of negative phase-sequence.Similarly, fundamental wave negative sequence component can be mentioned using the SAI schematic diagram of negative phase-sequence
It takes.
Fig. 6 is the amplitude-frequency characteristic figure of fundamental wave negative sequence.As the π of ω=- 100, since SAI is -50Hz's for input signal
Negative-sequence signals have the ability of polarity selection, have filter action to the signal of other frequencies.Therefore SAI structure is that one kind has
Polarity selects the bandpass filter of characteristic, can be applied to the Harmonic currents detection of active filter.
Fig. 7 is the SAI filter structure block diagram of fundamental frequency of the invention.The fundamental positive sequence electric current i extracted with SAI+ α1、i+ β1By total current iα、iβAfter making the difference, using SAI fundamental extraction link, while the fundamental positive sequence electric current i extracted+ α1、i+ β1
Output.In this way, turning again to while output by total current iα、iβLink is made the difference, so recycles, extracts more accurate fundamental wave
Forward-order current i+ α1、i+ β1。
Fig. 8 is that harmonic current of the invention obtains figure.By to fundamental positive sequence electric current i+ α1、i+ β1Extraction repeatedly, carry out
Operation makes threephase load electric current iabcSubtract three-phase fundamental positive sequence electric current i+ abc1Obtain more accurately harmonic current i* abc。
Embodiment described above only describe the preferred embodiments of the invention, not to model of the invention
It encloses and is defined, without departing from the spirit of the design of the present invention, those of ordinary skill in the art are to technical side of the invention
The various changes and improvements that case is made should all be fallen into the protection scope that claims of the present invention determines.
Claims (1)
1. a kind of no phase-locked loop formula SAI harmonic current detecting method for omitting Park transformation, which is characterized in that the method step
It is as follows:
Step 1, simplifying ip-iqIn the case where method system structure, load-side three-phase current is extracted, converts and transports by Clark
It calculates, obtains the electric current under two-phase stationary coordinate system；
Step 2, the extraction of SAI link fundamental positive sequence is carried out to the electric current under two-phase stationary coordinate system；
Step 3, the operation of Clark inverse transformation is carried out to the fundamental positive sequence electric current extracted, obtains the fundamental positive sequence electric current of three-phase；
Step 4, harmonic current is extracted on the basis of three-phase fundamental positive sequence electric current.
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