CN106026094B - A kind of unbalance control algorithm applied to active filter - Google Patents

A kind of unbalance control algorithm applied to active filter Download PDF

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Publication number
CN106026094B
CN106026094B CN201610258088.6A CN201610258088A CN106026094B CN 106026094 B CN106026094 B CN 106026094B CN 201610258088 A CN201610258088 A CN 201610258088A CN 106026094 B CN106026094 B CN 106026094B
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axis
current
active
fundamental wave
fundamental
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CN106026094A (en
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刘希
刘一希
仇志凌
张明
葛文海
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NANJING APAITEK TECHNOLOGY Co Ltd
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NANJING APAITEK TECHNOLOGY Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/20—Active power filtering [APF]
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

Abstract

The invention discloses a kind of unbalance control algorithms applied to active filter, first by DFT algorithms, extract the active and reactive electric current in load current；Then, active and reactive electric current is subjected to PARK transformation respectively, stable DC component is obtained after filtering；Active and reactive d axis, q axis are separately summed, d axis, the q axis DC quantities of fundamental negative sequence current are obtained, to derive the virtual value of fundamental negative sequence current and to the angle of network voltage；Active zero sequence is added with idle zero sequence obtains fundamental wave zero sequence electric current, and zero-sequence current orthogonal two DC quantities under power frequency are obtained by DFT algorithms；Finally, the virtual value of three-phase fundamental wave out-of-balance current is obtained with the cosine law.The present invention can quickly calculate the virtual value of the fundamental wave unbalanced component in power grid, avoid through property at a slow speed of summing point by point caused by evolution, and according to the data of calculated real-time update, realize the correlation functions such as the amplitude limit of compensation.

Description

A kind of unbalance control algorithm applied to active filter
Technical field
The present invention relates to control method of the active filter under uneven operating mode, it is related specifically to how quickly to obtain base The method of wave imbalance virtual value.
Background technology
Active Power Filter-APF (APF) is a kind of dynamic compensating device, can be quick to the harmonic wave in power grid, idle progress Response, and increasingly attract attention.And currently, certain application scenarios need to put into a large amount of single-phase load, such case is usual Occur when individual user is using large capacity, uneven single-phase load.In addition, energy imbalance may also be due to three phase mains band Caused by different loads or certain large-scale three-phase equipments operate under the conditions of unbalanced power grid, such as the arc-welding etc. in industry Equipment causes power grid serious imbalance occur.Three-phase imbalance can cause many drawbacks：
(1) presence of three-phase imbalance load, transformer station high-voltage side bus cause loss to increase, in addition, three-phase in asymmetric operating mode Load unbalanced that zero-sequence current will be caused excessive, localized metallic part Wen Sheng increases, and may lead to transformer damage；
(2) on the other hand, three-phase load unbalance, a phase or two-phase are abnormal heavy, will increase the voltage drop in circuit, reduce Power quality, the electric appliance for influencing user use；
Industry-by-industry is increasing to energy demand, especially more and more big to high quality electrical energy demands.This requires must Power quality must be improved.Energy use efficiency is improved, it is each as country and industrial economy to improve power quality, oneself warp of reduction energy consumption The common recognition of industry.Therefore, active filter improves device as power quality, and can compensate for uncompensated load becomes becoming for certainty Gesture.
Active Power Filter-APF will realize the compensation control of unbalanced load, need to extract negative phase-sequence and zero in fundamental current Order components, currently used is the PARK transformation based on coordinate transform theory, after reversion PRAK transformation, by three-phase electricity rheology It changes under two-phase rotating coordinate system, by the input signal to d axis or q axis after filtered as inverse transformation, obtains fundamental wave Negative phase-sequence, zero-sequence current, to extract the unbalanced component in uncompensated load.In addition, as active filter, equipment Capacity limit is certainly existed, then the virtual value for how quickly obtaining unbalanced component in uncompensated load, which becomes, calculates amplitude limit system Several keys.Currently, the use of wider method being the point-by-point cumulative mode for seeking evolution, this mode is usually required by a base Wave period can just calculate virtual value, and usually such virtual value calculation is not a week in active filter control Phase updates primary, that is to say, that real amplitude limit will have longer delay, and capability of fast response is poor.
Invention content
The technical problem to be solved by the present invention is to existing extraction fundamental wave imbalances, calculate the computational methods of virtual value, deposit In longer delay, capability of fast response is poor, cannot be satisfied the needs actually controlled.
In order to solve the above technical problems, the technical solution adopted by the present invention is：A kind of injustice applied to active filter Weigh control algolithm, includes the following steps：Step 1：By DFT algorithms, fundamental active, the fundamental wave reactive power electricity in load current are extracted Stream；Step 2：Fundamental active, the fundamental reactive current that step 1 is obtained carry out PARK transformation respectively, and fundamental active inverts PARK Transformation obtains d axis, q axis components, obtains stable DC component after filtered, fundamental wave reactive power reversion PARK convert to obtain d axis, Q axis components obtain stable DC component after filtered；Step 3：The active d axis obtained in step 2 is folded with idle d axis Add, active q axis is superimposed with idle q axis, obtains d axis, the q axis DC quantities of fundamental negative sequence current；Step 4：Solve right angled triangle Active negative phase-sequence virtual value is found out, and angle of the A phases fundamental negative sequence current to network voltage A phases is obtained according to d axis, the positive and negative of q axis, And then B phases, C phases negative-sequence current are found out to the angles of network voltage A phases according to three-phase angular relationship；Step 5：Fundamental wave zero sequence is distinguished It is multiplied with sine table, cosine table and carries out the cumulative averaging of half period, orthogonal components x, y are obtained with this, solve straight Angle triangle finds out the virtual value of fundamental wave zero sequence, and according to the x of component, and y is positive and negative to obtain fundamental wave zero sequence Current on Grid voltage A phases Angle, and then find out B phases, C with respect to network voltage A phases angle；Step 6：Based on the angle that step 4 and step 5 obtain, meter The differential seat angle between three-phase fundamental wave negative sequence and zero sequence is calculated, the cosine law is recycled to find out active uneven virtual value.
The present invention is by rotating forward PARK transformation, reversion PARK is converted and respectively obtained watt current, the positive sequence of reactive current, bears Sequence, zero-sequence current, to obtain fundamental negative sequence current, fundamental wave zero sequence electric current and fundamental wave imbalance total current；Not according to fundamental wave It balances virtual value and equipment rated capacity obtains corresponding limiting figure；It is squared and caused this method avoid adding up point by point Limiting figure updates slower drawback, is capable of the variation of quick response load within several cycles, updates limiting figure.
Specifically, the filtering mode of the step 2 is filtered using sliding window.
It is an advantage of the invention that：The virtual value that the fundamental wave unbalanced component in power grid can quickly be calculated, avoids logical Property at a slow speed is crossed caused by point-by-point summation evolution, and according to the data of calculated real-time update, realizes the correlations such as the amplitude limit of compensation Function.
Description of the drawings
Fig. 1 is d, q coordinate system schematic diagram.
Fig. 2 is fundamental negative sequence current angular distribution relational graph.
Fig. 3 is zero sequence DFT DC component schematic diagrames.
Fig. 4 is fundamental wave zero sequence current angle distribution relation figure.
Fig. 5 is that the cosine law calculates schematic diagram.
Specific implementation mode
The method of the present invention is described further below by attached drawing.
The method of the present invention includes the following steps：
First by DFT algorithms, fundamental active, the fundamental reactive current in load current are extracted, it is specific as follows：
(1) according to Fourier decomposition, i will be loadedLa(t),iLb(t),iLc(t), it is expressed as form：
When N=1, fundamental active component, reactive component as in the load current, i.e.,：
iLxa,b,c(t)=a1sinwt,iLya,b,c(t)=b1coswt
(2) three-phase that obtains DFT algorithms is active, three-phase is idle carries out PARK transformation respectively, obtains active reversion d axis, q Axis component dxn, qxn；Idle reversion d axis, q axis components dyn, qyn；And active zero sequence, idle zero sequence iLnx0, iLny0, it will Dxn, qxn, dyn, qyn, referring in particular to following transformation for mula：
CLARK changes three-phase static coordinate system of changing commanders is transformed into α, and under β coordinate systems, transformation for mula is：
PARK changes are changed commanders α, and under β coordinate system transformations to d, q coordinate system rotated, transformation for mula is：
Wherein, θ is the phase angle obtained by network voltage phaselocked loop, reversion coordinate system use-θ.
3, watt current, the zero-sequence component of reactive current in load are sought:
(3) sliding window filter, AC compounent therein is filtered out, obtain stable DC component Idxn, Iqxn, Idyn, Iqyn；
(4) active and reactive d axis, q axis are separately summed, obtain d axis, the q axis DC quantities of fundamental negative sequence current, according to Right angled triangle corner relationship and the cosine law obtain the virtual value of fundamental negative sequence current and the angle to network voltage, tool Body method is as follows：
As shown in Figure 1, Va is network voltage A phases, q+ is to rotate forward q axis, and q- is overturning q axis,Then fundamental wave is negative Sequence current effective value is：Three-phase negative/positive current effective value is identical；According further to d, q axis it is positive and negative may determine that θ as Limit, to obtain angle ψ of the A phases fundamental negative sequence current to network voltage A phasesA, it is contemplated that reversion coordinate q axis and rotating forward coordinate q Axis differs 180 °.
As shown in Fig. 2, be quadrant judgment mode, according to the judgment mode, obtain B phases, C with respect to network voltage angle, I.e.
ψA+ 120 °, ψA-120°。
(5) as shown in figure 3, active zero sequence is added with idle zero sequence obtains fundamental wave zero sequence electric current, which is done into DFT Algorithm obtains zero-sequence current orthogonal two DC quantity I under power frequency0x, I0y,。
As shown in Figure 1,Then fundamental negative sequence current virtual value is：Three-phase zero-sequence current virtual value It is identical.
As shown in figure 4, being quadrant judgment mode, judgment mode combination I0x、I0yPositive and negative determining zero sequence angle ψ0。
(6) as shown in figure 5, according to be previously obtained virtual value, angle, utilize the cosine law to obtain three-phase fundamental wave uneven The virtual value of electric current.φ is the differential seat angle of fundamental wave negative sequence and fundamental wave zero sequence；I0For zero-sequence current virtual value；InHave for negative-sequence current Valid value；In0For fundamental wave out-of-balance current virtual value.
Fundamental wave out-of-balance current virtual value be fundamental wave negative sequence, fundamental wave zero sequence it is vector superposed, can be asked according to the cosine law The virtual value of fundamental wave out-of-balance current is obtained, specific formula is as follows：
Comprehensive calculating above can be with, you can finds out each phase fundamental wave out-of-balance current virtual value, the virtual value and specified appearance Amount compares, and obtains corresponding limiting figure, for the follow-up functions such as virtual value amplitude limit extend when fundamental wave imbalance compensation.

Claims (2)

1. a kind of unbalance control algorithm applied to active filter, which is characterized in that include the following steps：
Step 1：By DFT algorithms, fundamental active, the fundamental reactive current in load current are extracted；
Step 2：Fundamental active, the fundamental reactive current that step 1 is obtained carry out PARK transformation respectively, and fundamental active inverts PARK Transformation obtains d axis, q axis components, obtains stable DC component after filtered, fundamental wave reactive power reversion PARK convert to obtain d axis, Q axis components obtain stable DC component after filtered；
Step 3：The active d axis obtained in step 2 is superimposed with idle d axis, active q axis is superimposed with idle q axis, and it is negative to obtain fundamental wave The d axis of sequence electric current, q axis DC quantities；
Step 4：It solves right angled triangle and finds out active negative phase-sequence virtual value, and A phase fundamental wave negative sequences are obtained according to d axis, the positive and negative of q axis The angle of Current on Grid voltage A phases, and then B phases, C phases negative-sequence current are found out to network voltage A phases according to three-phase angular relationship Angle；
Step 5：Fundamental wave zero sequence electric current is multiplied with sine table, cosine table respectively carries out the cumulative averaging of half period, is obtained with this Orthogonal components x, y are obtained, solves the virtual value that right angled triangle finds out fundamental wave zero sequence electric current, and according to the x of component, y is just It is negative obtain the angle of fundamental wave zero sequence Current on Grid voltage A phases, and then find out B phases, C phase zero sequence Current on Grid voltage A phases Angle；
Step 6：Based on the angle that step 4 and step 5 obtain, the differential seat angle between three-phase fundamental wave negative sequence and zero sequence, then profit are calculated The virtual value of fundamental wave out-of-balance current is found out with the cosine law.
2. a kind of unbalance control algorithm applied to active filter according to claim 1, it is characterised in that：It is described The filtering mode of step 2 is filtered using sliding window.
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CN107356813A (en) * 2017-07-17 2017-11-17 南京亚派科技股份有限公司 A kind of harmonic wave extracting method applied to active filter
CN111208340A (en) * 2020-02-26 2020-05-29 泰州学院 Single-phase fundamental wave reactive current accurate detection method based on Fourier transform
CN112448412A (en) * 2020-10-28 2021-03-05 爱士惟新能源技术(扬中)有限公司 Control method for low voltage ride through of photovoltaic inverter

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CN1996698A (en) * 2006-12-18 2007-07-11 西安交通大学 Control method for the mixing compensation system of the active power filter and parallel capacitor
EP2398124A1 (en) * 2010-06-18 2011-12-21 Alstom Technology Ltd Method to minimize input current harmonics of power systems such as ESP power systems
CN103683292A (en) * 2013-12-30 2014-03-26 武汉光谷电气有限公司 Parallel type quasi-proportional resonance active power filter and control method thereof
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

Patent Citations (5)

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Publication number Priority date Publication date Assignee Title
CN1450704A (en) * 2002-04-05 2003-10-22 清华大学 Method for compensating dynamic three-phase imbalance load and compensator
CN1996698A (en) * 2006-12-18 2007-07-11 西安交通大学 Control method for the mixing compensation system of the active power filter and parallel capacitor
EP2398124A1 (en) * 2010-06-18 2011-12-21 Alstom Technology Ltd Method to minimize input current harmonics of power systems such as ESP power systems
CN103683292A (en) * 2013-12-30 2014-03-26 武汉光谷电气有限公司 Parallel type quasi-proportional resonance active power filter and control method thereof
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