CN108462177A - A kind of serial active filter and system of gird-connected inverter - Google Patents
A kind of serial active filter and system of gird-connected inverter Download PDFInfo
- Publication number
- CN108462177A CN108462177A CN201810088135.6A CN201810088135A CN108462177A CN 108462177 A CN108462177 A CN 108462177A CN 201810088135 A CN201810088135 A CN 201810088135A CN 108462177 A CN108462177 A CN 108462177A
- Authority
- CN
- China
- Prior art keywords
- fundamental
- amplifier
- filter
- grid
- gird
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
-
- 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
- Y02E40/40—Arrangements for reducing harmonics
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Power Conversion In General (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a kind of serial active filter of gird-connected inverter and systems, belong to electric-power filter technical field.Serial active filter includes transformer, voltage source inverter unit, current detecting unit, fundamental detecting unit, the first amplifier, the second amplifier, PWM drive signal generation unit.When serial active filter is applied in the grid-connected system in parallel of multiple three-phase grid-connected inverters, the serial active filter of a set of gird-connected inverter is used alone in each phase of each gird-connected inverter.The present invention separately designs fundamental wave and harmonic wave according to circuit add-up principle, improve the filtering performance of gird-connected inverter, cumbersome filter parameter is avoided to design and frequency resonance problems, further decrease grid-connected harmonic pollution and power attenuation, ensure the stability of grid-connected inverter system, and obtains good filter effect.
Description
Technical field
The invention belongs to electric-power filter technical fields, more particularly, to a kind of series connection type active of gird-connected inverter
Filter and system.
Background technology
In the case where the fossil energies such as conventional oil, coal and natural gas are increasingly deficient, energy and environment problem is increasingly
It is prominent.Nearly ten years, the renewable new energies such as wind-force and photovoltaic are quickly grown, and distributed generation system, which generates electricity by way of merging two or more grid systems, to be obtained
Extensive concern, shows booming trend.With the continuous improvement of distributed generation system permeability, single inverter
Capacity be difficult to meet the needs of grid-connected scale, and the grid-connected system that multiple inverter parallels collectively constitute becomes point
The mark of cloth power generation large-scale application.Gird-connected inverter accesses the key equipment of power grid as renewable energy power generation, extensively
Applied to the grid type interface in distributed grid-connected electricity generation system, AC microgrids and the DC bus in direct-current micro-grid and power grid
The fields such as interface, performance quality directly influence entire grid-connected system.Therefore the topological structure of gird-connected inverter, filtering
Device and control mode have become the emphasis of current scholars' research.
What photovoltaic generation, fuel cell etc. were sent out is direct current, it is necessary to be reverse into the alternating current ability for meeting grid requirements
It realizes grid-connected.However gird-connected inverter generally uses high-frequency PWM pulsewidth modulation, can lead to a large amount of switching frequency subharmonic current
Into power grid, interference can be generated to other EMI sensitive equipments in power grid in this way, it is necessary to install filtering additional between power grid and inverter
Device.Early stage, inverter improved networking electric current using L and LC filters simple in structure in small-power inversion grid connection electricity generation system
Quality, and had more mature achievement in research.But in middle high power applications occasion, need to increase filter inductance value
Ideal current harmonics elimination effect can be reached, this not only lowers the dynamic properties of system, also bring component size it is excessive, at
A series of problems, such as this is excessively high.
For the deficiency of L filters, many scholars propose to replace L filters to be filtered with LCL filter.Compared to L
Mode filter, when reaching identical high-frequency harmonic inhibition, the total inductance amount needed for LCL type filter is than L-type filter
It is much smaller, switching frequency harmonic wave can be inhibited well, reduce filter volume weight, therefore be increasingly being applied to
High-power gird-connected inverter equipment.However, LCL filter itself is a underdamping third-order system, when design, not only needs
Three parameters of Exact Design, including two inductance values and a capacitance, parameters have its filtering performance important
It influences, causes its design complex.And there are intrinsic frequency resonant points for LCL filter itself, inevitably to be
System brings resonance problems.
For configuring the inverter of LCL filter, since the size of filter parameter directly affects systematic entirety energy,
Therefore, would generally consider when carrying out LCL parameter designings claimed below：
(1) limitation of total inductance amount.Impedance voltage drop under rated condition need to be less than the 10% of network voltage.
(2) to the limitation of filter capacity.Excessive filter capacitor will generate a large amount of reactive loss, reduce inversion
The overall power processing capacity of device.
(3) design limitation of resonant frequency.In order to avoid resonant frequency becomes the restriction of inverter current controller design
Factor is general to require the resonant frequency of the LCL filter designed between 10 times of fundamental frequencies and 0.5 times of switching frequency.
(4) using passive damping resistance scheme when, to damping resistance RdLimitation.Work as RdWhen bigger, resonance peak reduces
It is more apparent, but the loss of filter also increases therewith, while filter will also decrease the filtering performance of high-frequency harmonic, in engineering
1/3 of condensance at resonant frequency is generally taken as to damping resistance.
As described above, the parameter designing of LCL filter is limited by many.Make a general survey of existing document, LCL filter and its
Modified has preferable application prospect, but its Parameters Optimal Design is still more difficult.
For resonance problems existing for LCL filter, there are many resonance suppressions that scholar discusses LCL type gird-connected inverter
System, the main passive damped method for including capacitive branch string resistance, split capacitor current control, using digital control delay and in electricity
After throttle regulator the method for additional character filter and based on capacitor current feedback, capacitance voltage feedback or multi-state variable group
Close the active damping control method of feedback.Preceding method can inhibit the resonance of LCL, but above-mentioned most of research only considers
Ideal power grid.And uncertainty existing for actual electric network can reduce system performance, or even generate unstable.
Compared with L-type filter, LCL filter is actually inductance to be utilized different frequency component is presented with capacitance
The characteristics of otherness of impedance, filter increase filter capacitor CfWith net side filter inductance L2, inductive branch under high frequency situations
Impedance is big, and capacitive branch impedance is small, introduces L2And CfIt afterwards can be to the inverter bridge output current i containing higher hamonic waveinvIt carries out
Parallel impedance shunts, filter capacitor CfLow impedance path is provided for high frequency section, it is humorous in injection power network current to effectively reduce
Wave current component.So inevitably, LCL filter also has certain shunting function, and larger filter to Fundamental-frequency Current
Wave inductance will also result in the loss of power transmission.
In addition, there are more low-frequency harmonics ingredients in actual electric network voltage, due to the limit of LCL filter design parameter
System, causes it poor to the inhibiting effect of low frequency harmonic content, low-frequency harmonics will produce distributed generation resource and grid entry point simultaneously
Raw pollution, or even cause the control of gird-connected inverter unstable.
In conclusion LCL filter is as the filter of gird-connected inverter, there are still many defects.Study a kind of filtering
Device, be applied to gird-connected inverter system in, improve the filtering performance of gird-connected inverter, further decrease grid-connected harmonic pollution and
Power attenuation avoids system resonance and ensures the stability of system, becomes the technical barrier of this field.
Invention content
For the disadvantages described above or Improvement requirement of the prior art, the present invention provides a kind of tandem types of gird-connected inverter to have
Source filter and system improve grid-connected inverse its object is to be separately designed to fundamental wave and harmonic wave according to circuit add-up principle
The filtering performance for becoming device avoids cumbersome filter parameter design and frequency resonance problems, further decreases grid-connected harmonic pollution
And power attenuation, ensure the stability of grid-connected inverter system, while obtaining good filter effect.
To achieve the above object, according to one aspect of the present invention, a kind of series connection type active of gird-connected inverter is provided
Filter.It includes transformer, voltage source inverter unit, current detecting unit, fundamental detecting unit, the first amplifier,
Two amplifiers, PWM drive signal generation unit；The current detecting unit respectively with the fundamental detecting unit and described second
Amplifier connects；The fundamental detecting unit is connect with first amplifier and second amplifier respectively；Described first
Amplifier and second amplifier are connect with the PWM drive signal generation unit respectively；The PWM drive signal generates single
It is first to be connected with the voltage source inverter unit；The voltage source inverter unit is connected with the Circuit Fault on Secondary Transformer winding；
The transformer primary winding is access grid-connected by circuit after connecting with the gird-connected inverter of distributed generation resource in micro-capacitance sensor
Point or load；
The current detecting unit is for detecting networking electric current and generating current signal；The fundamental detecting unit is for examining
It surveys the fundamental wave component of current signal and generates fundamental current signal；First amplifier is used to amplify fundamental current signal and give birth to
At first via reference signal；Second amplifier is used to subtract current signal the harmonic current of gained after fundamental current signal
Signal amplification generates the second tunnel reference signal；Two-way reference signal is superimposed by the PWM for driving signal generating unit, and is obtained
Obtain PWM drive signal；The voltage source inverter unit is used to be controlled and be generated by PWM drive signal to be believed with the reference after being superimposed
It is passed through the Circuit Fault on Secondary Transformer winding after number proportional electric current is filtered.
Preferably, the serial active filter is phase structure.
Preferably, control parameter α is arranged by first amplifier, control parameter is arranged by second amplifier
β；The setting of control parameter α and β meet following rule：
Fundamental wave and harmonic wave are separately designed according to circuit add-up principle, presented in fundamental wave minimum, almost
The impedance for being zero makes the fundamental wave component of networking electric current almost nondestructively pass through filter；Big impedance is presented in harmonic wave, makes
The harmonic components of networking electric current are greatly decayed, and become minimum relative to fundamental wave component, i.e., almost nil；
The fundamental wave equiva lent impedance of the serial active filterFor：
Wherein,For the fundamental voltage at the transformer primary winding both ends,For the transformer primary side around
The fundamental current of group, Z1 (1)For the fundamental wave leakage reactance of the primary side of the transformer, Z1 (1)=Z1, Zm (1)For the base of the transformer
Wave excitation impedance, Zm (1)=Zm, α is fundamental wave control parameter；
The nth harmonic equiva lent impedance of the serial active filterFor：
Wherein,For the nth harmonic voltage at the transformer primary winding both ends,It is primary for the transformer
The nth harmonic electric current of side winding, β are harmonic controling parameter；
Serial active filter control parameter proposed by the present invention only has α and β, and is real number digital parameters, designs pole
It is simple, and cumbersome parameter designing is not present.Control parameter α and β are set by the first amplifier and the second amplifier, reasonable
In the case that control parameter α and β are set, fully meet grid-connected required filter effect.Due to serial active filter original
Reason is filtered by shunting, almost lossless to the fundamental wave component of electric current, and very little is lost in filter power.Due to tandem type
Active filter is equivalent to the impedance of resistance sense in micro-capacitance sensor when stable state, without the interconnection of inductance and capacitance, therefore not
There are frequency resonance problems.Therefore it is intrinsic to can be very good solution LCL filter for serial active filter proposed by the present invention
Defect problem, be well suited for that LCL filter is replaced to undertake the filtering requirements of gird-connected inverter.
It is another aspect of this invention to provide that it is inverse to provide a kind of multiple three-phase grids of the application serial active filter
Become device parallel connection grid-connected system, which is characterized in that each three-phase grid-connected inverter includes that three sets of single-phase series types are active
Filter.
Monophase system is referred under the three-phase system containing multiple gird-connected inverters, in each of each gird-connected inverter
Serial active filter proposed by the present invention is used alone in phase.Each single-phase series type active filter puts on three-phase line
Big device individually controls, and is independent of each other when breaking down.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, can obtain down and show
Beneficial effect：
(1) present invention separately designs fundamental wave and harmonic wave according to circuit add-up principle, and pole is presented in fundamental wave
Small impedance, is essentially close to short circuit, and the fundamental wave component of networking electric current is made almost nondestructively to pass through filter；Harmonic wave (no matter
High order or low order) in the case of great impedance is presented, so that the harmonic components of networking electric current is greatly decayed, relative to fundamental wave
Ingredient becomes minimum, has good filter effect；
(2) natural resonance point is not present, when stable state is equivalent to the access resistance emotional resistance in microgrid, and capacitance does not connect
Enter, there is no the risks for causing system resonance, ensure that the stability of grid-connected inverter system；
(3) control parameter α and β are rationally arranged by the first amplifier and the second amplifier, do not need cumbersome parameter and sets
Meter, control method are simple；
(4) different from the principle of LCL filter, without the shunting of fundamental wave and harmonic wave, and impedance of fundamental frequency is minimum, therefore filtering is led
The power attenuation very little of cause, is equivalent to the impedance of resistance sense in micro-capacitance sensor when stable state, frequency resonance problems are not present.
(5) it is applied in the grid-connected system in parallel of multiple three-phase grid-connected inverters, each phase list of each gird-connected inverter
The serial active filter for solely using a set of gird-connected inverter, does not interfere with each other when breaking down, and fully meets grid-connected required
Filter effect.
Description of the drawings
Fig. 1 is that LCL filters single-phase grid-connected inverter system construction drawing in present pre-ferred embodiments；
Fig. 2 is that LCL filters single-phase grid-connected inverter electric current amplitude/phase characteristic curves figure in present pre-ferred embodiments；
Fig. 3 is the structural schematic diagram that the present invention is applied to single-phase grid-connected inverter system in present pre-ferred embodiments；
Fig. 4 is transformer T-type equivalent circuit diagram in present pre-ferred embodiments；
Fig. 5 is system Fundamental Wave Equivalent Circuit figure in present pre-ferred embodiments；
Fig. 6 is system harmonics equivalent circuit diagram in present pre-ferred embodiments；
Fig. 7 is the structural representation that the present invention is applied to multiple three-phase grid-connected inverter systems in present pre-ferred embodiments
Figure.
Specific implementation mode
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
It does not constitute a conflict with each other and can be combined with each other.
Gird-connected inverter serial active filter proposed by the invention is for traditional gird-connected inverter LCL filtering
Parameter designing existing for device and optimization are difficult, cause system unstable there are natural resonance point and transmit work(caused by shunting
Rate is lost larger many defects to be designed.
Embodiment 1：
First the basic principle of LCL filter and resonance mechanism are illustrated first.Fig. 1 is that LCL filtering is single-phase grid-connected inverse
Become device system construction drawing.Wherein inverter side inductance L1, net side inductance L2Single-phase grid-connected inverter LCL filters are constituted with filter capacitor C
Wave device, ugFor grid entry point voltage, line impedance Z is expressed as Z=R+jX, and wherein R is line resistance, and j is imaginary symbols, and X is line
Road reactance.DC bus-bar voltage UdcIt converts, is generated containing near a large amount of switching frequency and its multiple frequency by gird-connected inverter
The inverter output voltage u of harmonic waveinv, the inverter output current i that is generated under systemic effectL1Make by the shunting of capacitance C
With the fundamental current of most harmonic current and fraction forms capacitance current iCAnd flowed through from capacitive branch, it is most
The harmonic current of fundamental current and fraction forms networking electric current igPower grid is flowed into, to reach filter effect.Above is exactly LCL
The basic principle of filter filtering.Since LCL filter is to reach filter effect by shunting, exist to fundamental current certain
Shunting function, therefore will produce a degree of power attenuation.
LCL filter is a third-order system, and there are two inductance element and a capacity cells.Because each inductance is first
The parameter of part and capacity cell all has substantial connection with system filter characteristic, therefore the parameter designing of LCL filter is extremely complex,
It needs to consider that factors and restrictive condition can be only achieved good filter effect.In addition to this, no matter how parameter designs, and makees
For a third-order system containing capacitance and inductance simultaneously, LCL filter necessarily contains that there are one intrinsic frequency resonant points.According to
Fig. 1, the output voltage u of gird-connected inverter in can deriving using s as the frequency domain of variableinvInverter side electric current i is arrived respectivelyL1With
Networking electric current igTransmission function be：
Fig. 2 is G1(s) and G2(s) the amplitude/phase characteristic curves figure of transmission function；It is known from figures that：LCL filter exists
One resonance angular frequency ωr, in ωrThere are a positive resonance spikes, phases, and -180 ° of saltus steps occur, are said from the angle of control at place,
This -180 ° of saltus steps are that primary bear is passed through, it will produce the closed-loop pole of a pair of of right half plane, cause gird-connected inverter to generate humorous
It shakes, is unable to stable operation.Above is exactly the resonance mechanism of LCL filter.
In order to solve the inherent shortcoming of LCL filter, propose with a kind of serial active filter generation provided by the invention
For in LCL filter access grid-connected inverter system.It is different from the basic principle and steady-state equivalent structure of LCL filter,
Overcome the inherent shortcoming of LCL filter.
The operation principle of serial active filter of the present invention is further described below.
It is illustrated in figure 3 serial active filter individual event Grid-connected inverter system structure chart.Serial active filter
With distributed generation resource UdcGird-connected inverter series connection after pass through the access grid-connected point of circuit.
Serial active filter of the present invention include transformer, voltage source inverter unit, current detecting unit,
Fundamental detecting unit, the first amplifier, the second amplifier, PWM drive signal generation unit.Current detecting unit respectively with fundamental wave
Detection unit is connected with the second amplifier；Fundamental detecting unit is connect with the first amplifier and the second amplifier respectively；First puts
Big device and the second amplifier are connect with PWM drive signal generation unit respectively；
Voltage source inverter unit includes LC filter circuits and voltage source inverter.LC filtered electrical routing capacitances CdAnd inductance
LdIt constitutes and voltage source inverter is connected, at the voltage source inverter switching frequency for filtering out serial active filter
Harmonic wave.
PWM drive signal generation unit is connected with voltage source inverter；Voltage source inverter and Circuit Fault on Secondary Transformer winding
Connection.U1For the voltage at transformer primary side both ends, U2For the voltage at Circuit Fault on Secondary Transformer both ends.Transformer primary side AX is micro-
Pass through the access grid-connected point of circuit (or load), Circuit Fault on Secondary Transformer ax after connecting with the gird-connected inverter of distributed generation resource in power grid
Connect voltage source inverter.Current detecting unit is for detecting networking electric current igAnd generate current signal；Fundamental detecting unit is used
In the fundamental wave component for detecting current signal；The fundamental wave component amplification of current signal is become the first via with reference to letter by the first amplifier
Number；Harmonic current signal amplification after second amplifier will remove fundamental wave component generates the second tunnel reference signal；Two-way is with reference to letter
Number superposition after be sent into PWM drive signal generation unit generate PWM drive signal, for control voltage source inverter generate and be superimposed
The proportional electric current of rear reference signal is passed through Circuit Fault on Secondary Transformer winding, make transformer primary side be equivalent to one to fundamental wave and
The impedance of different resistance sense values is presented in harmonic wave.
Fig. 4 is the T-type equivalent circuit diagram of transformer.The phasor expression formula of transformer voltage equation can be obtained by Fig. 4：
U1=I1Z1+(I1+I′2)Zm (3)
-U′2=I '2Z′2+(I1+I′2)Zm (4)
U1For the voltage at transformer primary winding both ends；U′2It is equivalent to change for the voltage at Circuit Fault on Secondary Transformer winding both ends
The voltage of depressor primary side；I1For transformer primary winding electric current, I in this example1=Ig, similarly hereinafter；I2' it is transformer secondary
The equivalent electric current to transformer primary side of side winding current, Z1For the primary side leakage reactance of transformer, ZmFor the excitation reluctance of transformer
It is anti-；Z′2For the equivalent leakage reactance to primary side of Circuit Fault on Secondary Transformer leakage reactance.
According to circuit add-up principle, if networking electric current igIncluding networking fundamental currentWith networking harmonic currentn
For overtone order, n>0, and n ≠ 1.Then by current detecting unit, fundamental detecting unit, the first amplifier, the second amplifier after
The reference signal being formed by stacking is：
Wherein, iref1It is first via reference signal, first via reference signal is through excessive current detection unit, fundamental detecting list
Reference signal after member, the first amplifier；iref2It is the second tunnel reference signal, the second tunnel reference signal is by current detecting list
Reference signal after member, fundamental detecting unit, the second amplifier；irefIt is that first via reference signal and the second tunnel reference signal are folded
Reference signal after adding；H is the gain for determining the current transformer used in networking electric current；k1For the times magnification of the first amplifier
Number；k2For the amplification factor of the second amplifier.Voltage source inverter VSI is used for DC side voltage of converter UdWhat is provided is straight
Stream signal is transformed into and irefThe alternating current I of same frequency2And enable its flow into Circuit Fault on Secondary Transformer winding.Inverter direct-flow side electricity
Press UdThere are three types of source modes：1) DC side connects a capacitor, makes DC-side Voltage Stabilization by controlling inverter；2) straight
Stream side connects an accumulator, and stable DC voltage is obtained by controlling inverter；3) electricity is taken by electric system induction, passed through
Over commutation obtains stable DC voltage.
To simplify the analysis, it is K inverter to be equivalent to gainPWMProportional component.Then Circuit Fault on Secondary Transformer winding current I2
For
KPWMFor the gain of inverter；The equivalent electric current I to transformer primary winding of Circuit Fault on Secondary Transformer winding current2′
For：
Wherein, kTFor the coupling no-load voltage ratio of transformer,α and β parameters in order to control.
According to circuit add-up principle, system can be divided into fundamental wave system and harmonic series system, and analyzed respectively.
Under fundamental wave system, it can be obtained by formula (5)Simultaneous formula (3)-(5), acquire transformer primary side
Fundamental wave equiva lent impedanceFor：
Z1 (1)For the fundamental wave leakage reactance of the primary side of transformer, Z1 (1)=Z1；Zm (1)For the fundamental wave excitation impedance of transformer, Zm (1)
=Zm,For the fundamental voltage at transformer primary winding both ends,For the fundamental current of transformer primary winding, α is
Fundamental wave control coefrficient.Optionally, if enablingThen
Fig. 5 is the Fundamental Wave Equivalent Circuit of system,Fundamental voltage is exported for gird-connected inverter,For grid entry point fundamental wave electricity
Pressure,For grid-connected fundamental current, line impedance Z(1)It is expressed as Z(1)=R(1)+jX(1), wherein R(1)For line resistance, j is imaginary number
Symbol, X(1)It is line reactance.Transformer primary winding can be equivalent in the case where ignoring error fundamental wave short at this time
The fundamental wave part on road, networking electric current almost can nondestructively flow into grid entry point.
Under harmonic wave system, it can be obtained by formula (5)Simultaneous formula (3)-(5), acquire transformer primary side
Nth harmonic equiva lent impedanceFor：
Z1 (n)For the nth harmonic leakage reactance of the primary side of transformer, Z1 (n)=nZ1；Zm (n)For the nth harmonic excitation of transformer
Impedance, Zm (n)=nZm,For the nth harmonic voltage at transformer primary winding both ends,For transformer primary winding
Nth harmonic electric current, β are harmonic controling coefficient.
Fig. 6 is the harmonic wave equivalent circuit of system,Nth harmonic voltage is exported for gird-connected inverter,For grid entry point n times
Harmonic voltage,For grid-connected nth harmonic electric current, line impedance Z(n)It is expressed as Z(n)=R(n)+jX(n), wherein R(n)For line electricity
Resistance, j is imaginary symbols, X(n)It is line reactance.Harmonic controling parameter beta is rationally set, then transformer primary winding relative harmonic
It is equivalent to big impedance, extraordinary decline can be played by networking harmonic current caused by the harmonic voltage to gird-connected inverter or grid entry point
Subtract effect.
In conclusion serial active filter proposed by the present invention, is harmonious to fundamental wave according to the principle of stacking of circuit
Wave is separately designed, and minimum impedance is presented in fundamental wave serial active filter, make the fundamental wave of networking electric current at
Divide and almost nondestructively passes through filter；Great impedance is presented in harmonic wave serial active filter, makes networking electric current
Harmonic components greatly decayed, it is minimum relative to fundamental wave component, rationally setting control parameter α and β in the case of, energy
It is enough fully to meet grid-connected required filter effect.
Serial active filter control parameter proposed by the present invention only has α and β, and is real number digital parameters, designs pole
It is simple, and cumbersome parameter designing is not present.Since serial active filter principle is filtered by shunting, to electricity
The fundamental wave component of stream is almost lossless, and very little is lost in filter power.Since serial active filter is in micro-capacitance sensor when stable state
It is equivalent to the impedance of resistance sense, without the interconnection of inductance and capacitance, therefore frequency resonance problems are not present.Therefore the present invention
The serial active filter of proposition can be very good to solve the intrinsic defect problem of LCL filter, be well suited for that LCL is replaced to filter
Device undertakes the filtering requirements of gird-connected inverter.
Embodiment 2：
Fig. 7 is the structural schematic diagram that serial active filter is applied to multiple three-phase grid-connected inverter systems.Such as Fig. 7 institutes
Show, monophase system is referred under the three-phase system containing multiple gird-connected inverters, in each phase of each gird-connected inverter
Serial active filter proposed by the present invention is used alone.Each series connection type active filter on serial active filter three-phase line
The amplifier of wave device individually controls, and is independent of each other when breaking down.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, all within the spirits and principles of the present invention made by all any modification, equivalent and improvement etc., should all include
Within protection scope of the present invention.
Claims (4)
1. a kind of serial active filter of gird-connected inverter, which is characterized in that it includes transformer, voltage source inverter list
Member, current detecting unit, fundamental detecting unit, the first amplifier, the second amplifier, PWM drive signal generation unit；The electricity
Stream detection unit is connect with the fundamental detecting unit and second amplifier respectively；The fundamental detecting unit respectively with institute
The first amplifier is stated to connect with second amplifier；First amplifier and second amplifier respectively with the PWM
Driving signal generating unit connects；The PWM drive signal generation unit is connected with the voltage source inverter unit；The electricity
Potential source inverter unit is connected with the Circuit Fault on Secondary Transformer winding；The transformer primary winding in micro-capacitance sensor with distribution
Pass through the access grid-connected point of circuit or load after the gird-connected inverter series connection of formula power supply；
The current detecting unit is for detecting networking electric current and generating current signal；The fundamental detecting unit is for detecting electricity
It flows the fundamental wave component of signal and generates fundamental current signal；First amplifier is used to fundamental current signal amplification generating the
Reference signal all the way；Second amplifier is used to subtract current signal the harmonic current signal of gained after fundamental current signal
Amplification generates the second tunnel reference signal；Two-way reference signal is superimposed by the PWM for driving signal generating unit, and is obtained
PWM drive signal；The voltage source inverter unit be used for by PWM drive signal control and generate be superimposed after reference signal
The Circuit Fault on Secondary Transformer winding is passed through after proportional electric current is filtered.
2. a kind of serial active filter of gird-connected inverter as described in claim 1, which is characterized in that the tandem type
Active filter is phase structure.
3. a kind of serial active filter of gird-connected inverter as claimed in claim 1 or 2, which is characterized in that pass through institute
The first amplifier setting control parameter α is stated, control parameter β is arranged by second amplifier；The setting of control parameter α and β
Meet following rule：
Fundamental wave and harmonic wave are separately designed according to circuit add-up principle, presented in fundamental wave minimum, almost nil
Impedance, so that the fundamental wave component of networking electric current is almost nondestructively passed through filter；Big impedance is presented in harmonic wave, makes networking
The harmonic components of electric current are greatly decayed, and become minimum relative to fundamental wave component, i.e., almost nil；
The fundamental wave equiva lent impedance of the serial active filterFor：
Wherein,For the fundamental voltage at the transformer primary winding both ends,For the transformer primary winding
Fundamental current, Z1 (1)For the fundamental wave leakage reactance of the primary side of the transformer, Z1 (1)=Z1, Zm (1)Fundamental wave for the transformer is encouraged
Magnetoimpedance, Zm (1)=Zm, α is fundamental wave control parameter；
The nth harmonic equiva lent impedance of the serial active filterFor：
Wherein,For the nth harmonic voltage at the transformer primary winding both ends,For the transformer primary side around
The nth harmonic electric current of group, β are harmonic controling parameter；
In the case of rationally setting control parameter α and β, fully meet grid-connected required filter effect.
4. a kind of application multiple three-phase grid-connected inverter parallel connection grid-connected systems according to claim 2 or 3, which is characterized in that every
A three-phase grid-connected inverter all includes three sets of single-phase series type active filters；In each phase of each three-phase grid-connected inverter
It is upper to be used alone the single-phase series type active filter, the amplifier list of each single-phase series type active filter on three-phase line
Solely control, is independent of each other when breaking down.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810088135.6A CN108462177A (en) | 2018-01-30 | 2018-01-30 | A kind of serial active filter and system of gird-connected inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810088135.6A CN108462177A (en) | 2018-01-30 | 2018-01-30 | A kind of serial active filter and system of gird-connected inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108462177A true CN108462177A (en) | 2018-08-28 |
Family
ID=63239377
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810088135.6A Pending CN108462177A (en) | 2018-01-30 | 2018-01-30 | A kind of serial active filter and system of gird-connected inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108462177A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109638894A (en) * | 2019-01-31 | 2019-04-16 | 张欣 | A kind of series connection adaptive stabilizer between gird-connected inverter and weak grid |
| CN110829485A (en) * | 2019-10-10 | 2020-02-21 | 国网湖南综合能源服务有限公司 | LCL filter parameter and control parameter global optimization design method, system and medium based on particle swarm optimization |
| CN112952903A (en) * | 2021-02-26 | 2021-06-11 | 云南电网有限责任公司保山供电局 | Current self-adaptive control method and control system based on weak power grid condition |
| CN113363984A (en) * | 2021-07-28 | 2021-09-07 | 广东电网有限责任公司 | Active filter and three-phase active filtering system |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107248743A (en) * | 2017-07-21 | 2017-10-13 | 华中科技大学 | A kind of active electric filter device for specifying subharmonic |
-
2018
- 2018-01-30 CN CN201810088135.6A patent/CN108462177A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107248743A (en) * | 2017-07-21 | 2017-10-13 | 华中科技大学 | A kind of active electric filter device for specifying subharmonic |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109638894A (en) * | 2019-01-31 | 2019-04-16 | 张欣 | A kind of series connection adaptive stabilizer between gird-connected inverter and weak grid |
| CN110829485A (en) * | 2019-10-10 | 2020-02-21 | 国网湖南综合能源服务有限公司 | LCL filter parameter and control parameter global optimization design method, system and medium based on particle swarm optimization |
| CN112952903A (en) * | 2021-02-26 | 2021-06-11 | 云南电网有限责任公司保山供电局 | Current self-adaptive control method and control system based on weak power grid condition |
| CN112952903B (en) * | 2021-02-26 | 2023-07-25 | 云南电网有限责任公司保山供电局 | Current self-adaptive control method and control system based on weak current network condition |
| CN113363984A (en) * | 2021-07-28 | 2021-09-07 | 广东电网有限责任公司 | Active filter and three-phase active filtering system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Luo et al. | Overview of power quality analysis and control technology for the smart grid | |
| CN102522879B (en) | Active damping method of LCL grid-connected inverter system and circuit for realizing active damping method | |
| Bhattacharya et al. | Parallel-connected shunt hybrid active power filters operating at different switching frequencies for improved performance | |
| Satyanarayana et al. | A critical evaluation of power quality features using Hybrid Multi-Filter Conditioner topology | |
| CN108462177A (en) | A kind of serial active filter and system of gird-connected inverter | |
| LV et al. | Power conversion in renewable energy systems: A review advances in wind and PV system | |
| Singh et al. | Review on power quality solution technology | |
| Zhang et al. | Harmonic resonance suppression strategy of the front-end Vienna rectifier in EV charging piles | |
| Kumar et al. | Power Quality Enhancement In 3-Phase 4-Wire Distribution System Using Custom Power Devices | |
| Hamadi et al. | A new hybrid series active filter configuration to compensate voltage sag, swell, voltage and current harmonics and reactive power | |
| Ramteke et al. | Design and comparative study of filters for multilevel inverter for grid interface | |
| Arulkumar et al. | Design of optimal LLCL filter with an improved control strategy for single phase grid connected PV inverter | |
| CN106208059B (en) | Adjustable impedance formula distributed photovoltaic power generation cluster resonance inhibiting system and suppressing method | |
| Kannan et al. | Power quality improvement using UPQC for grid interconnected renewable energy sources | |
| Swetha et al. | Reactive power control and harmonic mitigation by using DSTATCOM with different controllers | |
| Latha et al. | Unified Power Quality Conditioner for voltage sag and harmonic mitigation of nonlinear loads | |
| Popescu et al. | A new design method of an LCL filter in active dc-traction substations | |
| Da Rocha et al. | Control Strategies for Multifunctional Active Front-End Converter in Oil and Gas Platforms | |
| Gupta et al. | Improved stability of a Grid-Interfaced Inverter Using an LCL filter | |
| Chavan et al. | Design of Active Power Filter for Grid Connected WECS | |
| Belenguer et al. | Distributed generation power inverters as shunt active power filters for losses minimization in the distribution network | |
| Kumar et al. | Integration Of UPQC With New Converter Transformer For Power Quality Improvement | |
| Gayatri et al. | Power Quality Enhancement of MMG using Active Custom Power Conditioner | |
| Yang et al. | Multi‐function combined operation and control strategy of electronic power transformer for power quality improvement | |
| Albu et al. | Hybrid active power filter connected to a photovoltaic array |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20180828 |
|
| WD01 | Invention patent application deemed withdrawn after publication |