CN107356813A - A kind of harmonic wave extracting method applied to active filter - Google Patents
A kind of harmonic wave extracting method applied to active filter Download PDFInfo
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- CN107356813A CN107356813A CN201710579556.4A CN201710579556A CN107356813A CN 107356813 A CN107356813 A CN 107356813A CN 201710579556 A CN201710579556 A CN 201710579556A CN 107356813 A CN107356813 A CN 107356813A
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Abstract
The invention discloses a kind of harmonic wave extracting method applied to active filter, extracts the idle and individual harmonic current in load current first：In preceding half period, by way of cumulative and be averaging, the DC quantity of fundamental wave and each harmonic is calculated, carries out of ac acquisition in the later half cycle, and obtain the maximum of peak point current to be compensated simultaneously.
Description
Technical field
The present invention relates to the method for the raising stability of a system of the active filter under the larger operating mode of the fluctuation of load, especially relate to
And to how to obtain it is to be compensated load maximum method.
Background technology
Active Power Filter-APF (APF) is a kind of dynamic compensating device, can be quick to the harmonic wave in power network, idle progress
Response, and increasingly attract attention.In application scenarios such as many industry, business, because the frequent Large Copacity of harmonic device etc. is thrown
Cut, easily cause equipment larger dash current occur during transient state regulation, and the dash current easily causes equipment to exist
Occur the fault messages such as excessively stream in running, and frequently the fluctuation of load then causes equipment can not be in stable operation all the time
State.
Active Power Filter-APF will realize power factor of electric network and THD compensation, it is necessary to idle in load current
And each harmonic is extracted, it is compensated by certain algorithm.At present, the method for conventional harmonic wave extraction is main
Have：(1) simulative method, the compensation characteristic of this method are influenceed by electric network impedance and running status, are easily produced with system
Raw resonance, less stable, therefore progressively digitized and substituted；(2) the ip-iq methods based on instantaneous reactive power theory, this
Three-phase is mainly transformed to two-phase by coordinate transform and carries out analysis detection, and the shadow not distorted by line voltage by kind method
Ring, this algorithm depends on the realization of digitlization low pass filter, and design one can meet property indices, again
Restriction filter exponent number is very difficult；(3) other intellectualized algorithms include Wavelet Transform, neural network etc.；
(4) fast Fourier decomposition method (FFT) and based on DFT algorithms etc. derived from FFT.
Prior art one：In a kind of synchronous rotating frame disclosed in Publication No. CN 104184148B patent document
Harmonic current gradation control method, the harmonic wave extracting mode that the invention is related to are mainly based upon synchronous rotating angle, need to
Certain subharmonic current of compensation is transformed on the synchronous rotating frame in same number rotary speed and direction, and by simple
Algorithmic transformation eliminates the exchange disturbance quantity brought by other asynchronous current components, so as to extract corresponding to this time compensation electric current
DC quantity.The control method when needing to compensate a variety of harmonic currents, it is necessary to using more rotating coordinate transformation,
And must be consistent with the electric current rotary speed of required compensation time, amount of calculation is added, and with the increasing of compensation number requirement
Add, it is desirable to which the speed species of reference axis rotation is more, considerably increases the amount of calculation of digit chip.
Prior art two：A kind of no accumulated error sliding window disclosed in Publication No. CN 104749435A patent document
DFT harmonic detecting methods, this method mainly first gather mains voltage signal, recycle Digital Phase-Locked Loop Technology to make line voltage
It is synchronous；DFT direct transforms are carried out to the load current signal x (t) of collection by sliding window iterative method, respectively obtain x-axis and y-axis point
Amount；The command signal of h subharmonic is finally determined, recycles the extraction each harmonic instruction of DFT inverse transformations.This method can be compared with
The fast idle and individual harmonic current obtained in load current, and then system command is obtained, but this method acquisition is to be compensated
Current maxima is more troublesome, need to be obtained by way of multicycle sliding window is averaged, therefore, it is impossible to be carried out with most fast speed
Peak value amplitude limit, therefore when and load compensation demand larger in the fluctuation of load is larger, usually occur causing due to the impact of transient state
Overcurrent phenomenon, cause equipment can not normal operation.
It is more difficult that the peak point current of load to be compensated is obtained by traditional DFT sliding-window iterative algorithms, need to be by multiple
Ask for, store, computing acquisition, reaction is slower, and peak point current effectively can not be extracted in time.Under normal circumstances, it is protection
Equipment by overload impact, must not limited by the real-time output to equipment, and this method easily causes larger impact electricity
Stream, so that equipment can not normal operation.
The content of the invention
In view of the defects and deficiencies of the prior art, the present invention intends to provide the stability that can improve equipment,
Ensure the harmonic wave extracting method of the stable operation of equipment in the case that the fluctuation of load is larger.
The problems of above-mentioned in order to solve, the technical solution adopted by the present invention is：
A kind of harmonic wave extracting method applied to active filter, specifically include following steps：
Step 1：System obtains external loading electric current by sampling；
Step 2：In first half cycle, load current and fundamental wave, the sine of each harmonic, cosine are multiplied accumulating respectively；
Step 3：After the cumulative half period, pass through the data that step 2 is drawn and corresponding multiplication, you can obtain fundamental wave
And the DC quantity on the positive peg of each harmonic, cosine axle；
Step 4：The later half cycle, by the DC quantity on positive peg, cosine axle respectively with each self-corresponding sinusoidal, cosine table
It is multiplied, you can fundamental wave and each harmonic are obtained, so as to realize the extraction of reactive current and harmonic current；
Step 5：After the later half cycle obtains fundamental wave and each secondary of ac, load electricity can be obtained by point-to-point comparison method
The maximum of portion of electrical current to be compensated in stream, the maximum of load is limited before control is compensated.
Further, the idle and individual harmonic current in load current is extracted first：In preceding half period, pass through
Mode that is cumulative and being averaging, the DC quantity of fundamental wave and each harmonic is calculated, of ac acquisition is carried out in the later half cycle,
And the maximum of peak point current to be compensated is obtained simultaneously.
In the present invention, comprising the following steps that for DC quantity is obtained：
(1) according to Fourier decomposition, i will be loadedLa(t),iLb(t),iLc(t), it is expressed as form：
When N=1,3,5..., fundamental wave, 3 subharmonic, 5 subharmonic as in the load current etc., i.e.,：
iLxa,b,c(t)=a1sin wt,iLya,b,c(t)=b1cos wt
(2) it is summation operation by Integral Transformation in preceding half period
(3) after half period sum-average arithmetic, you can obtain the DC quantity of fundamental wave reactive power and each harmonic, i.e. iLnx,
iLny, wherein n expression overtone orders, the positive peg DC quantity of x expressions, y expression cosine axle DC quantities.
The present invention has the beneficial effect that：Compared with prior art, in being loaded fundamental wave to be compensated and each time it is humorous
Ripple content, and the maximum of load current to be compensated can be obtained in the later half cycle, it is easy to implement the safeguard measures such as peak value amplitude limit.
It is larger in the fluctuation of load, when there is instantaneous overload, increase the stability of system, reduce dash current, ensure the fluctuation of load compared with
Equipment remains to stable operation in the case of big；The maximum of load current is obtained in half period, realizes corresponding amplitude limit control
System, so as to ensure while correctly harmonic wave abstraction function is realized, to add stability, prevent equipment from the failures such as excessively stream occur.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, detailed description below, to this hair
It is bright to be further elaborated.It should be appreciated that embodiment described herein is only to explain the present invention, and do not have to
It is of the invention in limiting.
A kind of harmonic wave extracting method applied to active filter, specifically include following steps：
Step 1：System obtains external loading electric current by sampling；
Step 2：In first half cycle, load current and fundamental wave, the sine of each harmonic, cosine are multiplied accumulating respectively；
Step 3：After the cumulative half period, with corresponding multiplication, you can obtain fundamental wave and the positive peg of each harmonic,
DC quantity on cosine axle；
Step 4：The later half cycle, by the DC quantity on positive peg, cosine axle respectively with each self-corresponding sinusoidal, cosine table
It is multiplied, you can fundamental wave and each harmonic are obtained, so as to realize the extraction of reactive current and harmonic current；
Step 5：After the later half cycle obtains fundamental wave and each secondary of ac, load electricity can be obtained by point-to-point comparison method
The maximum of portion of electrical current to be compensated in stream, the maximum of load is limited before control is compensated.
Further, the idle and individual harmonic current in load current is extracted first：In preceding half period, pass through
Mode that is cumulative and being averaging, the DC quantity of fundamental wave and each harmonic is calculated, of ac acquisition is carried out in the later half cycle,
And the maximum of peak point current to be compensated is obtained simultaneously.
In the present invention, comprising the following steps that for DC quantity is obtained：
(1) according to Fourier decomposition, i will be loadedLa(t),iLb(t),iLc(t), it is expressed as form：
When N=1,3,5..., fundamental wave, 3 subharmonic, 5 subharmonic as in the load current etc., i.e.,：
iLxa,b,c(t)=a1sin wt,iLya,b,c(t)=b1cos wt
(2) it is summation operation by Integral Transformation in preceding half period
(3) after half period sum-average arithmetic, you can obtain the DC quantity of fundamental wave reactive power and each harmonic, i.e. iLnx,
iLny, wherein n expression overtone orders, the positive peg DC quantity of x expressions, y expression cosine axle DC quantities.
It is described above, it is merely illustrative of the technical solution of the present invention and unrestricted, those of ordinary skill in the art are to this hair
The other modifications or equivalent substitution that bright technical scheme is made, without departing from the spirit and scope of technical solution of the present invention,
It all should cover among scope of the presently claimed invention.
Claims (2)
1. a kind of harmonic wave extracting method applied to active filter, specifically include following steps：
Step 1：System obtains external loading electric current by sampling；
Step 2：In first half cycle, load current and fundamental wave, the sine of each harmonic, cosine are multiplied accumulating respectively；
Step 3：After the cumulative half period, pass through the data that step 2 is drawn and corresponding multiplication, you can acquisition fundamental wave and
DC quantity in the positive peg of each harmonic, cosine axle；
Step 4：In the later half cycle, the DC quantity on positive peg, cosine axle is multiplied with each self-corresponding sinusoidal, cosine table respectively,
Fundamental wave and each harmonic are can obtain, so as to realize the extraction of reactive current and harmonic current；
Step 5：After the later half cycle obtains fundamental wave and each secondary of ac, obtained by point-to-point comparison method in load current and wait to mend
The maximum of portion of electrical current is repaid, the maximum of load is limited before control is compensated.
A kind of 2. harmonic wave extracting method applied to active filter as described in right 1, it is characterised in that：Extraction load first
Idle and individual harmonic current in electric current：In preceding half period, by way of cumulative and be averaging, base is calculated
The DC quantity of ripple and each harmonic, of ac acquisition is carried out in the later half cycle, and obtain peak point current to be compensated simultaneously most
Big value.
In the present invention, comprising the following steps that for DC quantity is obtained：
(1) according to Fourier decomposition, i will be loadedLa(t),iLb(t),iLc(t), it is expressed as form：
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When N=1,3,5..., fundamental wave, 3 subharmonic, 5 subharmonic as in the load current etc., i.e.,：
iLxa,b,c(t)=a1sin wt,iLya,b,c(t)=b1cos wt
(2) it is summation operation by Integral Transformation in preceding half period
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(3) after half period sum-average arithmetic, you can obtain the DC quantity of fundamental wave reactive power and each harmonic, i.e. iLnx,iLny,
Wherein n represents overtone order, and x represents positive peg DC quantity, and y represents cosine axle DC quantity.
Comprehensive calculating above, fundamental wave to be compensated and each harmonic content in being loaded, and can be in second half
Phase obtains the maximum of load current to be compensated, is easy to implement the safeguard measures such as peak value amplitude limit.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02287808A (en) * | 1989-04-28 | 1990-11-27 | Fuji Electric Co Ltd | Control system for reactive power compensating device |
| CN101997314A (en) * | 2010-11-19 | 2011-03-30 | 长沙理工大学 | Control method and system for selectively compensating wattless power by active filter |
| CN104020351A (en) * | 2014-06-24 | 2014-09-03 | 哈尔滨同为电气股份有限公司 | Subharmonic detection method suitable for APF (Active Power Filter) under load unbalance system |
| CN106026094A (en) * | 2016-04-22 | 2016-10-12 | 南京亚派科技股份有限公司 | Imbalance control algorithm applied to active filter |
| CN106324342A (en) * | 2016-08-22 | 2017-01-11 | 江苏南自通华电力自动化股份有限公司 | Harmonic wave detecting method based on table look-up |
-
2017
- 2017-07-17 CN CN201710579556.4A patent/CN107356813A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02287808A (en) * | 1989-04-28 | 1990-11-27 | Fuji Electric Co Ltd | Control system for reactive power compensating device |
| CN101997314A (en) * | 2010-11-19 | 2011-03-30 | 长沙理工大学 | Control method and system for selectively compensating wattless power by active filter |
| CN104020351A (en) * | 2014-06-24 | 2014-09-03 | 哈尔滨同为电气股份有限公司 | Subharmonic detection method suitable for APF (Active Power Filter) under load unbalance system |
| CN106026094A (en) * | 2016-04-22 | 2016-10-12 | 南京亚派科技股份有限公司 | Imbalance control algorithm applied to active filter |
| CN106324342A (en) * | 2016-08-22 | 2017-01-11 | 江苏南自通华电力自动化股份有限公司 | Harmonic wave detecting method based on table look-up |
Non-Patent Citations (1)
| Title |
|---|
| 李昱等: ""一种基于正交定理的分次谐波电流检测算法"", 《大功率变流技术》 * |
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