CN106300354B - A kind of adaptive voltage feed-forward control compensation method of grid-connected converter - Google Patents
A kind of adaptive voltage feed-forward control compensation method of grid-connected converter Download PDFInfo
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- H—ELECTRICITY
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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
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Abstract
The present invention discloses a kind of adaptive voltage feed-forward control compensation method of grid-connected converter, belongs to the current control field of grid-connected converter (including inverter and rectifier).This method comprises the following steps：Sample point of common coupling network voltage, and using the voltage as the input signal of the adaptive voltage feed-forward control compensation of grid-connected converter, the input signal generates one group of output signal via the bandpass filter at one group of harmonic frequency in parallel, and each individual output signals in this group of output signal are carried out to be added the voltage signal generated for feedforward compensation；Resonance detector is carried out to each individual output signals simultaneously, when detecting that the amplitude of some output signal is uprushed, is removed related output signal from the voltage signal for feedforward compensation according to adaptive logic.The present invention has the advantages that the strong adaptability to wide variation electric network impedance, current on line side is superior in quality, design is convenient.
Description
Technical field
The present invention relates to a kind of adaptive voltage feed-forward control compensation methodes of grid-connected converter, belong to grid-connected converter (packet
Include inverter and rectifier) current control field.
Background technology
With flourishing for new energy distributed grid-connected power generation, grid-connected converter obtains extensively as its key component
Concern.And the current transformer of pulse modulation technology is used to generate a large amount of switching frequency subharmonic.Between current transformer and power grid
Access filter can effectively inhibit harmonic wave.Common filter includes L and LCL filter.It is higher grid-connected to realize
Power factor and lower current on line side harmonic distortion, existing scholar propose a large amount of grid-connected converter control method.But
It is that existing more mature control method only accounts for ideal power grid.Actual electric network (exactly, point of common coupling
(point of common coupling, PCC)) existing for uncertain factor can deteriorate system performance, even result in shakiness
It is fixed.On the one hand, there are abundant low-frequency harmonics ingredients in network voltage at PCC points；On the other hand, it is contemplated that longer power transmission and distribution
Circuit, more isolating transformer, a large amount of Distributed-generation equipment are mounted on the factors such as PCC, and power grid exists centainly at PPC points
Impedance and perception is generally presented in lower frequency ranges.
To overcome network voltage low-frequency harmonics to be distorted the influence to current on line side quality, a kind of method is to utilize harmonic resonance
The high open-loop gain of controller realizes preferable harmonics restraint, and this method needs for multiple harmonic using the control of multiple resonance
Device；Another kind of method is to improve current on line side quality using voltage feed-forward control.In contrast, voltage feed-forward control compensates
The dynamic response that grid-connected converter can also be optimized other than it can improve current on line side quality, has been widely used.But
Off the net in the light current that electric network impedance be can not ignore, network voltage (exactly, PCC voltages) feedforward compensation can lead to current on line side
There is even more serious harmonic distortion even to occur unstable and trigger grid-connected converter protection.It is unstable existing to solve system
As thering is scholar to propose and the fundamental wave component of PCC voltages being only used for feedforward compensation.This method solve light current grid-connected converters off the net
Device instability problem, but this method sacrifices the compensation of PCC electric voltage feed forwards to the rejection ability of current on line side harmonic wave, is unfavorable for carrying
High light current grid-connected converter current on line side quality off the net.
The above analysis, current on line side is humorous caused by the compensation of PCC electric voltage feed forwards can preferably inhibit network voltage distortion
Wave, but be easy to cause system stability variation in light current feedforward compensation off the net and cause serious current on line side harmonic distortion.
Existing typical case's feedforward compensation method is difficult to take into account the stability and current on line side quality of light current grid-connected converter off the net.
Therefore, optimize field in grid-connected converter current quality, need to study and a kind of adapt to include the various of light current net
Power grid occasion takes into account stability and current on line side quality and realizes convenient voltage feed-forward control compensation method.
Invention content
The present invention provides a kind of adaptive voltage feed-forward control compensation methodes of grid-connected converter, have to becoming on a large scale
Strong adaptability, the current on line side of changing electric network impedance be superior in quality, the convenient advantage of design, is suitable for single-phase and three-phase L filtering simultaneously
The current on line side or unsteady flow of the current control of net current transformer, single-phase and three-phase LCL filtering and other patterns filtering grid-connected converter
Device side current control.
The present invention is to solve its technical problem to adopt the following technical scheme that：
A kind of adaptive voltage feed-forward control compensation method of grid-connected converter, includes the following steps：
(1) sampling point of common coupling network voltage ug, and certainly using the point of common coupling network voltage as grid-connected converter
Adapt to the input signal of voltage feed-forward control compensation, the input signal via one group of frequency in parallel is 1,3 ... n times of fundamental wave
One group of bandpass filter output signal of bandpass filter and generation at frequency, is denoted as u respectivelyg_1、ug_3、…ug_n, the group is defeated
The each independent bandpass filter output signal gone out in signal is respectively fed to Resonance detector module and adaptive logic module；
(2) each bandpass filter output signal passes through Resonance detector module, and generation signal amplitude or virtual value change defeated
Go out information, and the information is sent into adaptive logic module；
(3) output information of Resonance detector module and each bandpass filter output signal pass through adaptive logic module,
The voltage signal u for feedforward compensation is generated according to adaptive logicg_ff。
Adaptive logic is in the step (3)：When detecting certain bandpass filter output signal ug_iAmplitude occur it is prominent
When increasing, by bandpass filter output signal ug_i~ug_nFrom feedforward offset voltage ug_ffMiddle removal；When detecting certain several band logical
Filter output signal ug_j~ug_iAmplitude when uprushing, then first by ug_i~ug_nFrom feedforward offset voltage ug_ffIn
It removes, continues to be detected each bandpass filter output signal after removal, if ug_j~ug_i-2It is still larger then by ug_i-2From feedforward
Offset voltage ug_ffMiddle removal, and so on, wherein i=3,5 ... n, j=3,5 ... n and j<i.
The voltage signal u of feedforward compensation is used for described in the step (3)g_ff, even ignore in electric network impedance very little
Under power grid occasion, ug_ffEqual to ug_1、ug_3、…ug_nThe sum of.
The voltage signal u of feedforward compensation is used for described in the step (3)g_ff, in the variation of electric network impedance wide range
Under power grid occasion, as electric network impedance gradually increases, successively from the voltage signal u for feedforward compensationg_ffMiddle removal ug_n、
ug_n-2、…ug_3。
The voltage signal u of feedforward compensation is used for described in the step (3)g_ff, in the prodigious power grid occasion of impedance, ug_ff
Equal to the fundamental wave component u of point of common coupling network voltageg_1。
Beneficial effects of the present invention are as follows：
1) grid-connected converter stronger stability when electric network impedance wide variation.
2) when electric network impedance wide variation and network voltage are distorted the excellent current on line side quality of grid-connected converter and
Preferably dynamic property.
4) it is measured woth no need to additional online or offline electric network impedance.
5) it is suitable for single-phase and three-phase L, LCL filtering and the filtering of other patterns grid-connected converter system.
Description of the drawings
Fig. 1 is the grid-connected converter system construction drawing using the method for the present invention, wherein：ugFor PCC voltages；igFor net side electricity
Stream；uinvFor grid-connected converter bridge arm output voltage；u1For the output of current regulator；u2For the output of feedforward compensation link；um
For modulating wave；kPWMIndicate current transformer bridge arm link gain；GL(s) or GLCL(s) it is filter link；Gh_1(s)、Gh_3
(s)、...、Gh_n(s) be 1,3 ..., the bandpass filter at n times of fundamental frequency；ug_1、ug_3、…ug_nFor Gh_1(s)、Gh_3
(s)、...、Gh_n(s) output signal；ug_ffFor the voltage signal for feedforward compensation；Gf(s) it is feedforward compensation link.
Fig. 2 is the single-phase LCL filtering gird-connected inverter circuit structure diagrams that the present invention is applied, wherein：L1For current transformer side
Inductance；C1For filter capacitor；L2For net side inductance；UdcFor DC bus-bar voltage；uinvFor grid-connected converter bridge arm output voltage；ig
For current on line side；iC1For capacitance current；ugFor PCC voltages；usFor ideal network voltage；ZgFor electric network impedance.
Fig. 3 is the double-current feedback control principle figure of conventional additional voltage feed-forward control compensation, wherein：L1For current transformer
Side inductance；C1For filter capacitor；L2For net side inductance；uinvFor grid-connected converter bridge arm output voltage；igFor current on line side；iC1For
Capacitance current；ugFor PCC voltages；usFor ideal network voltage；ZgFor electric network impedance；u1For the output of current regulator；u2For
The output of feedforward compensation link；umFor modulating wave；kPWMIndicate current transformer bridge arm link gain；Gf(s) it is feedforward compensation link；Gc
(s) it is current regulator；kCFor capacitance current proportional feedback factor；irefFor given current reference.
Fig. 4 is system open loop Bode diagram when electric network impedance is larger under Fig. 3 control programs, wherein：β is indicated in electric network impedance
Perceptual weight is the same as the ratio between inverter total inductance value itself.
Fig. 5 is the double-current feedback control principle figure of the adaptive voltage feed-forward control compensation method of the additional present invention, wherein：
L1For current transformer side inductance；C1For filter capacitor；L2For net side inductance；uinvFor grid-connected converter bridge arm output voltage；igFor net
Side electric current；iC1For capacitance current；ugFor PCC voltages；usFor ideal network voltage；ZgFor electric network impedance；u1For current regulator
Output；u2For the output of feedforward compensation link；umFor modulating wave；kPWMIndicate current transformer bridge arm link gain；Gf(s) it is feedforward
Compensation tache；Gc(s) it is current regulator；kCFor capacitance current proportional feedback factor；irefFor given current reference；Gh_1
(s)、Gh_3(s)、...、Gh_n(s) be 1,3 ..., the bandpass filter at n times of fundamental frequency；ug_1、ug_3、…ug_nFor Gh_1
(s)、Gh_3(s)、...、Gh_n(s) output signal；ug_ffFor the voltage signal for feedforward compensation.
Fig. 6 is system open loop Bode diagram when adaptive logic module does not work in Fig. 5 control programs and electric network impedance is larger,
Wherein：β indicates the perceptual weight in electric network impedance with the ratio between inverter total inductance value itself；ug_ffFor the electricity for feedforward compensation
Press signal；ug_1、ug_3、ug_5、ug_7For the output signal of bandpass filter at 1,3,5,7 times of fundamental frequency.
Fig. 7 is system open loop baud when adaptive logic module works normally under Fig. 5 control programs and electric network impedance is larger
Figure, wherein：β indicates the perceptual weight in electric network impedance with the ratio between inverter total inductance value itself；ug_ffTo be used for feedforward compensation
Voltage signal；ug_1、ug_3、ug_5For the output signal of bandpass filter at 1,3,5 times of fundamental frequency.
Fig. 8 is grid-connected converter operational process and network voltage current waveform after electric network impedance is uprushed under Fig. 5 control programs
Figure, wherein：β indicates the perceptual weight in electric network impedance with the ratio between inverter total inductance value itself；ug_5、ug_7For 5,7 times of fundamental waves
The output signal of bandpass filter at frequency；igFor current on line side；ugFor PCC voltages；T is the time.
Fig. 9 is current on line side and PCC voltage transient waveforms under Fig. 3 control programs, wherein：β is indicated in electric network impedance
Perceptual weight is the same as the ratio between inverter total inductance value itself；igFor current on line side；ugFor PCC voltages；T is the time.
Figure 10 is current on line side and PCC voltage transient waveforms under Fig. 5 control programs, wherein：β is indicated in electric network impedance
Perceptual weight is the same as the ratio between inverter total inductance value itself；igFor current on line side；ugFor PCC voltages；T is the time.
Specific implementation mode
Below with reference to attached drawing, technical scheme of the present invention is described in detail.
The present invention provides a kind of grid-connected converter voltage feed-forward control compensation method, as shown in Figure 1, it is suitable for single-phase and
The current control of three-phase L filtering grid-connected converters, single-phase and three-phase LCL filtering, the other patterns of single-phase and three-phase filter grid-connected change
Flow the current on line side or current transformer side current control of device.When implementing, sampling point of common coupling network voltage (is denoted as the method
ug), and using the point of common coupling network voltage as the input signal of the adaptive voltage feed-forward control compensation of grid-connected converter, institute
State input signal via one group of harmonic frequency in parallel (i.e. frequency be 1,3 ... n times of fundamental frequency) at bandpass filter production
Raw one group of bandpass filter output signal (is denoted as u respectivelyg_1、ug_3、…ug_n), by each independent band in this group of output signal
Pass filter output signal is respectively fed to Resonance detector module and adaptive logic module.In Resonance detector module, to each band
Pass filter output signal ug_3、…ug_nIt is monitored and each signal amplitude or virtual value change information is sent into adaptive logic
Module；In adaptive logic module, according to adaptive logic and the output information of Resonance detector module, by each bandpass filter
Output signal be added generating (is denoted as u for the voltage signal of feedforward compensationg_ff).Wherein, adaptive logic is：Work as detection
(it is denoted as u to certain bandpass filter output signalg_i, i=3,5 ... when amplitude n) is uprushed, which is exported
Signal ug_i~ug_nFrom feedforward offset voltage ug_ffMiddle removal；When detecting that certain several bandpass filter output signal (is denoted as ug_j
~ug_i, i=3,5 ... n, j=3,5 ... n and j<I) when amplitude is uprushed, then first by ug_i~ug_nFrom feedforward compensation
Voltage ug_ffMiddle removal continues to be detected each bandpass filter output signal after removal, if ug_j~ug_i-2It is still larger then
ug_i-2From feedforward offset voltage ug_ffMiddle removal, and so on.
By taking a single-phase LCL filtering grid-connected converter system as an example, specific example explanation is given below.
Single-phase LCL shown in Fig. 2 filters gird-connected inverter, by bridge type inverse topology, inverter side inductance L1, filter capacitor
C1With net side inductance L2Composition.In example, DC voltage UdcFor 400V, ideal network voltage usFor 220V/50Hz, specified work(
Rate 5kW, inductance L1For 0.75mH, L2For 0.45mH, filter capacitor C1For 6.8 μ F, switching frequency 15kHz.In example, ZgFor
Perception, i.e.,：
Zg=β (L1+L2)s (1)
In formula, β indicates power grid emotional resistance value with the ratio between inverter total inductance value itself；S is the complex frequency in complex frequency domain
Variable.
Fig. 3 is the block diagram of the double-current feedback control (being denoted as control schemes) of additional voltage feed-forward control compensation.By
In light current actual network voltage sampling location off the net be PCC points, thus the input of feedforward compensation link be PCC voltages ug, i.e.,：
(subscript " _ sample " indicates PCC voltage samples value)
ug_sample=ug=us+ig·Zg (2)
In formula, igFor current on line side.
Thus, off the net in the light current of electric network impedance wide range variation, voltage feed-forward control compensation and electric network impedance make
There are an additional current on line side positive feedback loop (feedback factor Z in Fig. 3g)。
I in Fig. 3 control schemesrefTo igOpen-loop transfer function be：(subscript " _ o " indicates open loop function)
In formula, kPWMIndicate current transformer bridge arm link gain；Gf(s) it is feedforward compensation link；Gc(s) it is current regulator；
kCFor capacitance current proportional feedback factor.
As can be seen that having had more a coefficient entry in the collective effect formula (3) of feedforward compensation and electric network impedance.
Fig. 4 gives open loop Bode diagram of the control schemes in electric network impedance wide variation.It is abundant in the phases of β=2
Degree has reduced to 14 °, and phase margin has reduced to 10 ° hereinafter, being greatly reduced for phase margin can cause in current on line side when β=3
Apparent increase is presented in low-frequency harmonics in 1kHz, is easy triggering grid-connected converter over-current over-voltage protection.Moreover, even more serious
It is that, with the gradual increase of electric network impedance, phase margin is finally less than 0 and keeps system unstable.Have voltage feed-forward control to mend
Compensation method is difficult to ensure the stable and preferable current on line side quality of light current grid-connected converter off the net.Thus, it is necessary to study one
It plants be suitable for the light current net occasion of electric network impedance wide variation, function admirable and realizes convenient voltage feed-forward control compensation
Method.
Fig. 5 gives grid-connected using the LCL filtering of the adaptive voltage feed-forward control compensation method of the present invention as shown in Figure 1
Inverter current control structure.In the method for the present invention, point of common coupling network voltage ugFirst via one group of harmonic wave frequency in parallel
Rate (i.e. frequency be 1,3 ... n times of fundamental frequency) at bandpass filter, bandpass filter Gh_n(s) expression formula is as follows：
In formula, ω0For network voltage fundamental wave angular frequency, ωcFor the pass band of bandpass filter.Bandpass filter exports
Signal ug_3、…ug_nInput Resonance detector module, ug_1、ug_3、…ug_nInput adaptive logic module.
In Resonance detector module, to ug_3、…ug_nSignal amplitude or virtual value be detected, when detecting certain signal
When uprushing, transmit this information in adaptive logic module.
In adaptive logic module, when Resonance detector module detects that certain bandpass filter output signal (is denoted as ug_i, i
=3,5 ... when amplitude n) is uprushed, by bandpass filter output signal ug_i~ug_nFrom feedforward offset voltage ug_ffIn
Removal；When detecting that certain several bandpass filter output signal (is denoted as ug_j~ug_i, i=3,5 ... n, j=3,5 ... n and j<
I) when amplitude is uprushed, then first by ug_i~ug_nFrom feedforward offset voltage ug_ffMiddle removal, after removal, gird-connected inverter
Continue to be detected each bandpass filter output signal while continuing to run with, if ug_j~ug_i-2It is still larger then by ug_i-2From
Feedforward compensation voltage ug_ffMiddle removal, and so on.
Specifically, in instances, ωcFor 50 π, n 7, that is, 1,3,5,7 band logical filter should be added when electric network impedance is not present
Wave device feedforward compensation.
Fig. 6 is the non-adjust automatically u of adaptive logic moduleg_ffWhen (ug_ff=ug_1+ug_3+ug_5+ug_7When) system open
Ring Bode diagram.At power grid no resistance (β=0), which will not have an impact system open loop magnitude-phase characteristics；β increases
11 ° are reduced to phase margin when 3, the harmonic current being also easy to produce in current on line side at corresponding frequencies (350Hz), and when β increases
It is unstable to system when 4.And after inventive method normal work, current on line side i when β increases to 3gIn 7 times and its time humorous nearby
Wave electric current increases and leads to PCC voltages ugIn 7 times and its nearby subharmonic voltage increases, Resonance detector module is by ug_7Signal is prominent
The information of increasing is sent to adaptive logic module.In turn, adaptive logic module judgement at this time should be by ug_7From feed-forward signal ug_ff
Middle removal.(u after the work of Resonance detector module when Fig. 7 is β=3g_ff=ug_1+ug_3+ug_5When) system open loop Bode diagram,
As it can be seen that by ug_7From ug_ffAfter middle removal, phase margin is significantly increased (about 40 °).As can be seen that using the present invention adaptive
It answers voltage feed-forward control compensation method that the stability of light current grid-connected converter current control off the net greatly improved, thus is conducive to
Optimize grid-connected converter stable state and dynamic response.
When Fig. 8 gives adaptive voltage feed-forward control compensation method using the present invention after electric network impedance is uprushed LCL
Filter the operational process and network voltage current waveform figure of gird-connected inverter.When electric network impedance is uprushed to β=5, due to electric current electricity
Pressure harmonic wave significantly increases, and the adaptive logic of method is first by u according to the present inventiong_7From ug_ffMiddle removal, and then it is each to continue monitoring
Secondary bandpass filter exports and continues from ug_ffMiddle removal ug_5.It can be seen that adaptive voltage feed-forward control using the present invention
Compensation method has substantially decayed light current current on line side harmonic wave off the net, improves current quality.
In addition, it is prominent to have carried out benchmark to the gird-connected inverter using control schemes and the method for the present invention in β=3
The test of change.Fig. 9 gives the transient response waveform of current on line side and PCC voltages under control schemes.Due in PCC voltages
Including the pressure drop on electric network impedance, PCC voltages certainly exist disturbance when current on line side is mutated, and result in dynamic response shown in Fig. 9
In larger overshoot and the oscillation of serious Current Voltage.Use the current on line side after the method for the present invention and PCC voltages
Transient response waveform is as shown in Figure 10, and the oscillation of overshoot reduction and Current Voltage in transient response substantially reduces.
To sum up, the adaptive voltage feed-forward control compensation method of grid-connected converter of the invention is effectively improved parallel network reverse
Stability of the device in electric network impedance wide variation, is effectively improved grid-connected converter current on line side quality and dynamic
Energy.Moreover, the method for the present invention measures woth no need to additional online or offline electric network impedance.
Since the control structure that single-phase and three-phase LCL filters voltage feed-forward control compensation in gird-connected inverter is similar,
And the method for the present invention can effectively improve the stability of gird-connected inverter and optimize stable state and dynamic response, thus can be extensive
Applied to various single-phase and three-phase LCL filtering gird-connected inverter current controls and need not additionally online or offline power grid resistance
Anti- measurement.
L filtering, LCL filtering and other forms filtering gird-connected inverter are distinguished as filter construction difference, and power grid
The position of electric voltage feed forward compensation signal used and feedforward compensation signal injection control loop is consistent, and the method for the present invention can
To effectively improve the stability of gird-connected inverter and optimize stable state and dynamic response, thus it can be widely applied to different filtering
It gird-connected inverter current control under device structure and does not need electric network impedance online or offline outside plus and measures.
Since the grid types such as reactive-load compensation, active power filtering, rectification are applied with the similitude controlled under inversion operating mode, this
Inventive method is also widely applied to the current control of various grid-connected systems and does not need power grid online or offline outside plus
Impedance measurement.
To sum up, the method for the present invention is other suitable for single-phase and three-phase L filtering, single-phase and three-phase LCL filtering, single-phase and three-phase
Form filters the current on line side or current transformer side current control of grid-connected converter, has to the strong suitable of wide variation electric network impedance
The advantage that Ying Xing, current on line side are superior in quality, design is convenient.
Above example is merely illustrative of the invention's technical idea, and protection scope of the present invention cannot be limited with this, every
According to technological thought proposed by the present invention, any change done on the basis of technical solution each falls within the scope of the present invention
Within.
Claims (5)
1. a kind of adaptive voltage feed-forward control compensation method of grid-connected converter, which is characterized in that include the following steps：
(1) sampling point of common coupling network voltage ug, and it is adaptively electric as grid-connected converter using the point of common coupling network voltage
The input signal of net electric voltage feed forward compensation, the input signal via one group of frequency in parallel is 1,3 ... at n times of fundamental frequency
Bandpass filter and generate one group of bandpass filter output signal, be denoted as u respectivelyg_1、ug_3、…ug_n, by this group of output signal
In in addition to ug_1Outer each independent bandpass filter output signal is sent into Resonance detector module, while in this group of output signal
Each independent bandpass filter output signal be sent into adaptive logic module；
(2) each bandpass filter output signal passes through Resonance detector module, generates signal amplitude or the output letter of virtual value variation
Breath, and the information is sent into adaptive logic module；
(3) output information of Resonance detector module and each bandpass filter output signal pass through adaptive logic module, foundation
Adaptive logic generates the voltage signal u for feedforward compensationg_ff。
2. the adaptive voltage feed-forward control compensation method of a kind of grid-connected converter according to claim 1, it is characterised in that：
Adaptive logic is in the step (3)：When detecting certain bandpass filter output signal ug_iAmplitude when uprushing, will
Bandpass filter output signal ug_i--ug_nFrom feedforward offset voltage ug_ffMiddle removal；When detecting that certain several bandpass filter is defeated
Go out signal ug_j--ug_iAmplitude when uprushing, then first by ug_i--ug_nFrom feedforward offset voltage ug_ffMiddle removal, removal
After continue to be detected each bandpass filter output signal, if ug_j--ug_i-2It is still larger then by ug_i-2From feedforward offset voltage
ug_ffMiddle removal, and so on, wherein i=5 ... n, j=3,5 ... n and j<i.
3. the adaptive voltage feed-forward control compensation method of a kind of grid-connected converter according to claim 1, it is characterised in that：
The voltage signal u of feedforward compensation is used for described in step (3)g_ff, under the power grid occasion that electric network impedance very little is even ignored,
ug_ffEqual to ug_1、ug_3、…ug_nThe sum of.
4. the adaptive voltage feed-forward control compensation method of a kind of grid-connected converter according to claim 1, it is characterised in that：
The voltage signal u of feedforward compensation is used for described in step (3)g_ff, under the power grid occasion of electric network impedance wide range variation, with
It electric network impedance gradually to increase, successively from the voltage signal u for feedforward compensationg_ffMiddle removal ug_n、ug_n-2、…ug_3。
5. the adaptive voltage feed-forward control compensation method of a kind of grid-connected converter according to claim 1, it is characterised in that：
The voltage signal u of feedforward compensation is used for described in step (3)g_ff, in the prodigious power grid occasion of impedance, ug_ffEqual to public coupling
The fundamental wave component u of point network voltageg_1。
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