CN103595051A - Harmonic current tracking control method for active power filter - Google Patents

Harmonic current tracking control method for active power filter Download PDF

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CN103595051A
CN103595051A CN201310608811.5A CN201310608811A CN103595051A CN 103595051 A CN103595051 A CN 103595051A CN 201310608811 A CN201310608811 A CN 201310608811A CN 103595051 A CN103595051 A CN 103595051A
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harmonic
amplitude
voltage
vhm
predetermined number
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谭光慧
谭敏刚
伍军胜
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Southeast University
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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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    • Y02E40/20—Active power filtering [APF]

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Abstract

The invention provides a harmonic current tracking control method for an active power filter. The cose idea is that harmonic currents are tracked and controlled in several times. The method mainly comprises the steps that load currents are tracked and detected, the amplitude and the phase of the harmonic currents which need to be restrained and are in assigned numbers are calculated according to actual needs, a calculated value and a reference value are subjected to subtraction, the difference value is compared with modulated waves after passing through a PI regulator, a drive circuit is driven to generate PWM control signals to drive a main circuit to generate harmonic voltages in assigned times, and the purpose of restraining harmonic waves is achieved. The method can effectively restrain the harmonic currents in assigned times, and properly compensate reactive power according to requirements.

Description

A kind of harmonic current tracking and controlling method for Active Power Filter-APF
Technical field
The tracking that the present invention relates to harmonic current is controlled, and relates in particular to a kind of Active Power Filter Harmonic Currents tracking and controlling method.
Background technology
Along with the fast development of power electronic technology, various nonlinear loads have brought a large amount of harmonic pollutions to electrical network.In order effectively to improve the quality of power supply, the drawback of traditional passive power filter highlights all the more, and novel Active Power Filter-APF (APF) technology is arisen at the historic moment.In APF technology, for the tracking of harmonic current, controlling is a key, is also a difficult point.
The control method of main flow has the methods such as triangle wave and stagnant ring control at present.The great advantage of triangle wave PWM current control method be switch in fixed frequency, but system responses is subject to the restriction of stabilization by current feedback, and is easily subject to the impact of load parameter.The advantage that stagnant ring is controlled PWM method is no stability problem, is simply easy to realize and fast response time, but its precision is subject to the impact of ring width, and high accuracy can cause switching frequency too high, and ring width fixedly causes switching frequency to change greatly.These shortcomings have all limited two kinds of methods in the application of some occasion.
System harmonics is done to fft analysis, and generally 5 times, 7 times, 11 times and 13 subharmonic are main components of harmonic current.Electrical network waveform after main times harmonic is suppressed, offset has approached sinusoidal, for the work of general device without affecting.
Summary of the invention
For the deficiencies in the prior art, and the feasibility of combining with theoretical analysis, the present invention proposes a kind of method that harmonic current minute secondary tracking is controlled, and main times harmonic in electrical network is followed the tracks of to control.
A method of dividing secondary tracking to control to harmonic current, comprises harmonic current detection computations module, PWM control module, main circuit power model and drive circuit.The present invention is knowing predetermined number of times harmonic current (amplitude A ihm, phase theta ihm) prerequisite under, to specifying subharmonic current to suppress, offsets, i.e. the present invention focuses on the gradation tracking and controlling method of consideration to harmonic current.And by controlling, the large I of regulation output bucking voltage realizes harmonic wave and suppresses.
Harmonic current detection computations module is core of the present invention, completes specifying detection and the calculating of subharmonic current amplitude, phase place, for PWM control module produces pwm waveform, provides foundation.PWM control module is to control the key that APF produces compensation harmonic electric current.PWM control module, power model and drive circuit coordinate harmonic current detection computations module to complete the tracking compensation of harmonic current.
The angle analysis of the root harmonic voltage that the present invention produces from harmonic current, by the amplitude A to predetermined number of times harmonic current ihmand phase theta ihmwith reference value
Figure BDA0000421908420000021
relatively produce pwm control signal, control inverter produces corresponding harmonic voltage.A wherein ihm, θ ihmcorresponding to the real-time parameter of the issued appointment of APF time compensation harmonic electric current,
Figure BDA0000421908420000022
in correspondence system, specify the real-time parameter of time harmonic current to be compensated.
Harmonic current detects, computing module, and this module is responsible for load current to carry out real-time tracking sampling, and according to actual needs, calculates the harmonic current electric parameters of predetermined number of times, comprises amplitude and phase place.
PWM control module, by the amplitude A of the predetermined number of times harmonic current drawing ihm, phase theta ihmrespectively with reference value
Figure BDA0000421908420000031
relatively; Its difference is comparing with high frequency triangle wave after pi regulator, through control circuit, produces pwm control signal.By the pwm control signal producing, drive main circuit output voltage amplitude and suitable predetermined number of times (m time) harmonic voltage of phase place again, to offset this subharmonic.
Beneficial effect:
This method can suppress predetermined number of times harmonic wave according to actual needs, has certain dynamic property and control precision, and PWM controller switches frequency is lower.The tracking that is applicable to various voltage type PWM pulse width modulated inverters is controlled.
Accompanying drawing explanation
Fig. 1 is embodiment of the present invention active power filter system figure;
Fig. 2 is embodiment of the present invention active power filter structure figure;
Fig. 3 is embodiment of the present invention gradation current tracking control principle drawing;
Fig. 4 is embodiment of the present invention Active Power Filter-APF main circuit diagram.
Wherein, in Fig. 1, e sfor the infinitely great power supply of electrical network; L is internal system impedance; i s, i lrepresent respectively system power, load current; Z lfor APF and electrical network are connected impedance when in parallel; V sand V orepresent respectively to connect impedance electrical network end, APF terminal voltage.
In Fig. 3, A ih5, A ih7a ihmrepresent respectively in offset current that APF sends in real time 5 times, 7 times ... m primary current amplitude size;
Figure BDA0000421908420000032
represent respectively to comprise in load current 5 times, 7 times ... m subharmonic amplitude reference value; θ ih5, θ ih7θ ihmrepresent respectively in offset current that APF sends in real time 5 times, 7 times ... m primary current phase place;
Figure BDA0000421908420000033
represent respectively to comprise in load current 5 times, 7 times ... m subharmonic current phase reference value; A vh5, A vh7a vhmrepresent respectively 5 times, 7 times ... m subharmonic voltage amplitude; θ vh5, θ vh7θ vhmrepresent respectively 5 times, 7 times ... m subharmonic voltage phase place; represent respectively fundamental voltage, 5 times, 7 times ... m subharmonic voltage (being phasor).
In Fig. 4, U srepresent Infinite bus system power supply; Z srepresent system impedance; E drepresent main circuit DC voltage; S 1-s 6represent transistor, L is parallel reactance.
Specific embodiment
Fig. 1 has described APF system configuration schematic diagram.
If line voltage is
Figure BDA0000421908420000042
(only containing first-harmonic,
Figure BDA0000421908420000043
), the reactor that APF is ZL by an impedance is in parallel with electrical network, establishes reactor APF terminal voltage to be
Figure BDA0000421908420000044
( V · o = V · o 1 + V · o 5 + V · o 7 + V · o 11 + V · o 13 ）。
Take 5 subharmonic currents as example
i h 5 = ( V 01 + V 05 ) - V S 1 Z L = ( V 01 - V S 1 ) Z L + V 05 Z L
Work as V o1=V s1time,
i h 5 = V 05 Z L
Now, APF only provides predetermined number of times harmonic voltage to system, plays harmonic wave inhibitory action.
Work as V o1≠ V s1time
Figure BDA0000421908420000048
produce predetermined number of times harmonic current, work the harmonic wave effect that suppresses.
( V 01 - V S 1 ) Z L ≠ 0
This part is no longer zero, can carry out reactive power compensation to system, rationally controls V 01-V s1positive and negative, size can effectively to system, carry out reactive power compensation.
By above-mentioned analysis, 5 subharmonic voltage V o55 subharmonic current i h5the reason producing.If will suppress 5 subharmonic currents, only need to produce corresponding 5 subharmonic voltages.5 subharmonic voltage V again o5by a constant (inductive impedance), determined in quantitative relation with 5 subharmonic currents.
Above-mentioned electric parameters can characterize by amplitude and phase place:
i h5＝A ih5sin(5ωt+θ ih5)，
In formula
A ih5represent 5 subharmonic current amplitudes;
ω represents first-harmonic angular speed under power frequency, i.e. ω=2 π f;
θ ih5the phase place that represents 5 subharmonic currents.
Therefore, knowing 5 subharmonic current amplitude A ih5, phase theta ih5situation under, can be by 5 subharmonic current amplitude A ih5, phase theta ih5control, realize the control of 5 subharmonic voltages output, thereby realize, eliminate the object of specifying subharmonic.
Fig. 2 has described the concrete part of APF.It comprises harmonic current detection module, predetermined number of times harmonic current computing module, predetermined number of times harmonic current tracking control module and four parts of main circuit.Wherein, harmonic current detection module is responsible for harmonic current to carry out real-time tracking detection; Predetermined number of times Harmonics Calculation module, according to user's request, calculates amplitude and the phase place of the harmonic current of predetermined number of times in total harmonic current; Harmonic current is followed the tracks of control module, adopts triangle wave PWM tracking control technology, and take respectively harmonic current, phase place is that control object produces PWM modulating wave; Main circuit structure is three-phase bridge type converter, and DC side adopts galvanic current source, and under control signal, main circuit can produce desirable appointment subharmonic voltage, thereby reaches the object that suppresses harmonic wave.
Fig. 3 has described core of the present invention: the principle of Active Power Filter-APF electric current gradation tracking and controlling method.Amplitude and the phase place of individual harmonic current of take is respectively control object, by by individual harmonic current amplitude, phase place and reference value comparison, exports amplitude, the phase place of each harmonic voltage after pi regulator.The amplitude of each harmonic voltage and phase place are synthesized after the sine wave of different frequency, different amplitudes again and fundamental voltage stack, obtain the modulating wave needing.By this ripple and triangle wave, by control circuit, produce pwm signal and drive main circuit to produce voltage again .
The every technology used of dealing with problems in the present invention mainly comprises the following aspects:
1. the detection of harmonic current, calculating
Extraction fundamental current and individual harmonic current amplitude, phase place are prerequisites of the present invention.After a large amount of harmonic waves superpose on first-harmonic, waveform is still cyclic variation, and amplitude and the phase place of according to existing theory and technology, extracting individual harmonic current are easy to realize, and for example, can, by using DSP to sample to load current, carry out fft analysis and address this problem.
2. the generation of predetermined number of times harmonic voltage
Harmonic current comes from harmonic voltage, has specific quantitative relation between harmonic voltage and harmonic current.By the control to harmonic current, comprise the control of amplitude and phase place, can realize the output of harmonic voltage is controlled.
Current and voltage harmonic can use respectively amplitude, phase place to characterize:
i hm＝A ihmsin(mωt+θ ihm)；
v hm＝A vhmsin(mωt+θ vhm)。
In formula
I hmrepresent m subharmonic current;
A ihmrepresent m subharmonic current amplitude;
ω represents fundamental current frequency;
θ ihmrepresent m subharmonic current phase place;
V hmrepresent m subharmonic voltage;
A vhmrepresent m subharmonic voltage amplitude;
θ vhmrepresent m subharmonic voltage phase place.
Shown in Fig. 3, with triangle wave PWM tracking and controlling method, realize the control to harmonic current, phase place, its essence is the difference of amplitude, phase place and reference quantity by relatively specifying subharmonic current, produce pwm signal and control main circuit switch break-make, realize the output of harmonic voltage.
Although illustrated and described embodiments of the invention, those having ordinary skill in the art will appreciate that: in the situation that not departing from principle of the present invention and aim, can carry out multiple variation, modification, replacement and modification to these embodiment, scope of the present invention is limited by claim and equivalent thereof.

Claims (4)

1. an Active Power Filter Harmonic Currents tracking and controlling method, its key step comprises:
To the sampling of electric power system load current, calculate according to demand the amplitude A of corresponding predetermined number of times harmonic current ihmand phase theta ihm, extract fundamental voltage in electric power system
Figure FDA0000421908410000011
According to corresponding control strategy, obtain the amplitude V of predetermined number of times harmonic voltage vhmand phase theta vhm;
According to the harmonic voltage of the harmonic voltage amplitude obtaining, the synthetic corresponding predetermined number of times of phase information
Figure FDA0000421908410000012
By fundamental voltage and the stack of each harmonic voltage, obtain modulating wave
Figure FDA0000421908410000013
According to the modulating wave of gained, adopt triangular wave comparison method to generate PWM start pulse signal and drive main circuit, realize the inhibit feature to predetermined number of times harmonic wave.
2. according to the control method of claim 1, predetermined number of times harmonic voltage amplitude V wherein vhmand phase theta vhmthe concrete grammar obtaining is as follows:
The amplitude A of each that Active Power Filter-APF is sent in real time time compensation harmonic electric current ihmand phase theta ihmrespectively with the amplitude of reference value harmonic current to be compensated
Figure FDA0000421908410000014
and phase place
Figure FDA0000421908410000015
it is poor to do, and its difference is inputted pi regulator, exports the amplitude V of each predetermined number of times harmonic voltage vhmand phase theta vhminformation.
3. according to the control method of claim 1, wherein said modulating wave generation method as follows:
According to the amplitude V of each predetermined number of times harmonic voltage obtaining vhmand phase theta vhminformation is synthesized corresponding subharmonic voltage signal
Figure FDA0000421908410000017
again by each harmonic voltage signal and fundamental voltage
Figure FDA0000421908410000018
by the adder modulating wave that superposes to obtain
Figure FDA0000421908410000019
4. according to the control method of claim 1, wherein generate PWM trigger impulse principle:
According to following formula, generate pwm pulse:
Wherein, x (t) is modulating wave, x c(t) be bipolarity triangular wave, Y (t) is pwm pulse.
CN201310608811.5A 2013-11-25 2013-11-25 Harmonic current tracking control method for active power filter Pending CN103595051A (en)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105743333A (en) * 2016-04-21 2016-07-06 哈尔滨理工大学 High-accuracy sine-wave variable-frequency power supply and implementation method thereof
CN105743104A (en) * 2016-04-25 2016-07-06 哈尔滨理工大学 Controller and control method for reactive compensation and low-order harmonic current suppression of power grid
CN105811419A (en) * 2016-04-25 2016-07-27 哈尔滨理工大学 Control method for accurately restraining power grid harmonics
CN105929720A (en) * 2016-06-17 2016-09-07 山东理工大学 Current tracking control method and device
CN107959289A (en) * 2017-11-30 2018-04-24 华夏天信（北京）智能低碳技术研究院有限公司 A kind of Active Power Filter-APF modified specifies subharmonic current compensating control method
CN107968578A (en) * 2017-12-08 2018-04-27 浙江大学 A kind of control method of reduction MMC submodule capacitor voltage stability bandwidths
CN110829432A (en) * 2019-10-14 2020-02-21 北京精密机电控制设备研究所 Amplitude limiting method of APF
WO2024066820A1 (en) * 2022-09-29 2024-04-04 中电普瑞电力工程有限公司 Harmonic voltage suppression method and system for hybrid dc transmission system, and device and medium

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105743333A (en) * 2016-04-21 2016-07-06 哈尔滨理工大学 High-accuracy sine-wave variable-frequency power supply and implementation method thereof
CN105743104A (en) * 2016-04-25 2016-07-06 哈尔滨理工大学 Controller and control method for reactive compensation and low-order harmonic current suppression of power grid
CN105811419A (en) * 2016-04-25 2016-07-27 哈尔滨理工大学 Control method for accurately restraining power grid harmonics
CN105811419B (en) * 2016-04-25 2018-08-21 哈尔滨理工大学 A kind of accurate control method for inhibiting mains by harmonics
CN105929720A (en) * 2016-06-17 2016-09-07 山东理工大学 Current tracking control method and device
CN105929720B (en) * 2016-06-17 2017-06-30 山东理工大学 A kind of curren tracing control method and device
CN107959289A (en) * 2017-11-30 2018-04-24 华夏天信（北京）智能低碳技术研究院有限公司 A kind of Active Power Filter-APF modified specifies subharmonic current compensating control method
CN107968578A (en) * 2017-12-08 2018-04-27 浙江大学 A kind of control method of reduction MMC submodule capacitor voltage stability bandwidths
CN107968578B (en) * 2017-12-08 2019-05-31 浙江大学 A kind of control method reducing MMC submodule capacitor voltage stability bandwidth
CN110829432A (en) * 2019-10-14 2020-02-21 北京精密机电控制设备研究所 Amplitude limiting method of APF
WO2024066820A1 (en) * 2022-09-29 2024-04-04 中电普瑞电力工程有限公司 Harmonic voltage suppression method and system for hybrid dc transmission system, and device and medium

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Application publication date: 20140219