CN114640123A - Feedforward control method and device of grid-connected inverter, medium and wind generating set - Google Patents

Feedforward control method and device of grid-connected inverter, medium and wind generating set Download PDF

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Publication number
CN114640123A
CN114640123A CN202011477703.5A CN202011477703A CN114640123A CN 114640123 A CN114640123 A CN 114640123A CN 202011477703 A CN202011477703 A CN 202011477703A CN 114640123 A CN114640123 A CN 114640123A
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voltage
grid
feedforward
connected inverter
capacitor
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阮景锋
郭锐
杨志千
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Xinjiang Goldwind Science and Technology Co Ltd
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Xinjiang Goldwind Science and Technology Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The feed-forward control method can include obtaining a first voltage based on a capacitance voltage of a capacitor in a filter connected to an output end of the grid-connected inverter; obtaining a second voltage by filtering the capacitor voltage; multiplying the first voltage by a first weighting coefficient to obtain a first weighted voltage; multiplying the second voltage by a second weighting coefficient to obtain a second weighted voltage; adding the first weighted voltage and the second weighted voltage to obtain a feedforward voltage control component; and controlling the grid-connected inverter based on the feedforward voltage control component. According to the feedforward control method and the feedforward control device of the grid-connected inverter, disclosed by the embodiment of the invention, the current harmonic of a grid-connected point can be reduced, and the phase angle stability margin is improved.

Description

Feedforward control method and device of grid-connected inverter, medium and wind generating set
Technical Field
The present invention generally relates to the field of grid-connected inverters, and more particularly, to a feedforward control method and apparatus for a grid-connected inverter, a medium, and a wind turbine generator system.
Background
With the gradual increase of the capacity of the wind generating set connected to the power grid, the harmonic waves of the grid-connected point of the wind generating set are more and more concerned by the power grid company, and the requirement on the performance of the grid-connected inverter is higher and higher.
Grid-connected inverters accessed into a wind power plant are scattered, and wiring impedance in the wind power plant is complex, so that the grid-connected inverters are required to have certain adaptability to power grid impedance, have adaptability to wide-range power grid impedance parameters, and can adapt to the operation requirements of both weak power grids and strong power grids.
The grid-connected electric energy quality is an important index of the grid-connected performance of the inverter, and the grid voltage feedforward can inhibit the influence of grid voltage harmonic waves on grid-connected current, improve the grid-connected current quality and improve the current response speed, so that the grid-connected electric energy quality is widely applied to the control of the grid-connected inverter.
However, a grid-connected current positive feedback loop is additionally introduced into the grid voltage feedforward, so that the stability margin of the system is greatly reduced, and the robust stability of the system to the grid impedance is reduced.
Furthermore, the phase angle stability margin in the capacitor voltage feedforward is also smaller.
Disclosure of Invention
An exemplary embodiment of the present invention is to provide a feedforward control method and a feedforward control apparatus for a grid-connected inverter, which can reduce current harmonics of a grid-connected point and improve a phase angle stability margin.
According to an aspect of the present invention, there is provided a feedforward control method of a grid-connected inverter, the feedforward control method including: obtaining a first voltage based on a capacitance voltage of a capacitor in a filter connected to an output terminal of the grid-connected inverter; obtaining a second voltage by filtering the capacitor voltage; multiplying the first voltage by a first weighting coefficient to obtain a first weighted voltage; multiplying the second voltage by a second weighting coefficient to obtain a second weighted voltage; adding the first weighted voltage and the second weighted voltage to obtain a feedforward voltage control component; and controlling the grid-connected inverter based on the feedforward voltage control component.
According to a preferred embodiment of the present invention, the step of obtaining the second voltage by filtering the capacitor voltage may include: the second voltage is obtained by band-pass filtering the capacitor voltage within a first frequency band.
According to a preferred embodiment of the present invention, the step of obtaining the first voltage based on the capacitance voltage of the capacitor in the filter connected to the output terminal of the grid-connected inverter may include: the first voltage is obtained by performing a transformation and/or filtering on the capacitor voltage, wherein the first voltage comprises a fundamental voltage component of the capacitor voltage.
According to a preferred embodiment of the present invention, the step of obtaining the first voltage by performing transformation and/or filtering on the capacitor voltage may comprise: the first voltage is obtained by performing a fast fourier transform on the capacitor voltage or by band-pass filtering the capacitor voltage in a second frequency band, wherein the first frequency band is wider than the second frequency band.
According to a preferred embodiment of the present invention, the feedforward control method may further include: obtaining a phase angle of the capacitor voltage, the step of obtaining the first voltage by performing a transformation and/or filtering on the capacitor voltage comprising: the method comprises the steps of performing rotation coordinate conversion on capacitor voltage based on a phase angle, performing low-pass filtering on the capacitor voltage under a rotation coordinate system, and performing rotation coordinate inverse conversion on the filtered voltage to obtain first voltage.
According to a preferred embodiment of the present invention, controlling the grid-connected inverter based on the feedforward voltage control component may include: obtaining an inductor current flowing through an inductor in a filter; obtaining a first output voltage according to the inductive current and the phase angle; and a pulse modulation unit controlling the grid-connected inverter based on a sum of the feedforward voltage control component and the first output voltage.
According to another aspect of the present invention, there is provided a computer-readable storage medium storing an instruction or a program, which when executed by a processor, implements the above feed forward control method.
According to another aspect of the present invention, there is provided a feedforward control apparatus of a grid-connected inverter, the feedforward control apparatus including: a first voltage obtaining unit configured to obtain a first voltage based on a capacitance voltage of a capacitor in a filter connected to an output terminal of the grid-connected inverter; a first filtering unit configured to obtain a second voltage by filtering the capacitor voltage; a first scaling unit configured to multiply the first voltage by a first weighting coefficient to obtain a first weighted voltage; a second scaling unit configured to multiply the second voltage by a second weighting coefficient to obtain a second weighted voltage; a first adder configured to add the first weighted voltage and the second weighted voltage to obtain a feedforward voltage control component; and the feedforward control unit is used for controlling the grid-connected inverter based on the feedforward voltage control component.
According to a preferred embodiment of the present invention, the first filtering unit may be configured to obtain the second voltage by band-pass filtering the capacitor voltage within a first frequency band.
According to a preferred embodiment of the present invention, the first voltage obtaining unit may be further configured to obtain the first voltage by performing transformation and/or filtering on the capacitance voltage, wherein the first voltage includes a fundamental voltage of the capacitance voltage.
According to a preferred embodiment of the present invention, the first voltage obtaining unit may be further configured to obtain the first voltage by performing a fast fourier transform on the capacitor voltage or by band-pass filtering the capacitor voltage within a second frequency band, wherein the first frequency band is wider than the second frequency band.
According to a preferred embodiment of the present invention, the feedforward control means may further include a phase-locked loop configured to obtain a phase angle of the capacitance voltage, and the first voltage obtaining unit is further configured to: the method comprises the steps of performing rotation coordinate conversion on capacitor voltage based on a phase angle, performing low-pass filtering on the capacitor voltage under a rotation coordinate system, and performing rotation coordinate inverse conversion on the filtered voltage to obtain first voltage.
According to a preferred embodiment of the present invention, the feedforward control unit may further include a current loop configured to obtain the first output voltage by using a phase angle and an inductor current flowing through an inductor in the filter, and a grid-connected inverter controller including: a second adder configured to add the feedforward voltage control component and the first output voltage to output a control voltage; and a pulse modulation unit configured to receive the control voltage and modulate according to the control voltage.
According to another aspect of the invention, a wind park is provided, comprising the above feed forward control apparatus.
According to the feedforward control device and the feedforward control method of the grid-connected inverter, detection and sampling of capacitor voltage are easier, and the system has high robustness and stability on power grid impedance.
Additional aspects and/or advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.
Drawings
The above and other objects and features of the exemplary embodiments of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings which illustrate exemplary embodiments thereof, wherein:
fig. 1 is a control block diagram showing a feedforward control apparatus of a grid-connected inverter according to a first embodiment of the invention;
fig. 2 is a control block diagram showing a feedforward control apparatus of a grid-connected inverter according to a second embodiment of the invention;
fig. 3 is a control block diagram showing a feedforward control device of a grid-connected inverter according to a third embodiment of the invention;
fig. 4 is a detailed configuration showing a first voltage obtaining unit included in the feedforward control apparatus of the grid-connected inverter of the first embodiment of the present invention.
Fig. 5 and 6 are flowcharts illustrating a feedforward control method of a grid-connected inverter according to an exemplary embodiment of the present invention;
FIG. 7 is an analysis plot of grid-connected current harmonics at capacitor voltage feed-forward;
FIG. 8 is an analysis plot of grid-connected current harmonics at capacitor voltage weighted feed-forward; and
fig. 9 is a comparative diagram of amplitude-frequency and phase-frequency characteristic curves of the output impedance of the grid-connected inverter corresponding to the capacitor voltage feedforward and the capacitor voltage weighted feedforward.
Detailed Description
Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.
The feedforward control method and the feedforward control device for the grid-connected inverter according to the embodiment of the invention can be applied to the grid-connected inverter in the field of wind power, but are not limited thereto.
According to the embodiment of the invention, the control strategy of capacitor voltage weighted feedforward is utilized to reduce the current harmonic of the grid-connected point and improve the phase stability margin of the system. Further, the embodiment according to the present invention obtains the weight component by filtering (e.g., band-pass filtering) the capacitor voltage, and superimposes (e.g., weighted-superimposes) it with the fundamental voltage weight component to obtain the control component.
Compared with control strategies such as power grid voltage feedforward, capacitance voltage direct feedforward and the like, the feedforward control device and the feedforward control method can obtain higher phase stability margin and have smaller total harmonic distortion.
Fig. 1 is a control block diagram showing a feedforward control apparatus of a grid-connected inverter according to a first embodiment of the present invention, fig. 2 is a control block diagram showing a feedforward control apparatus of a grid-connected inverter according to a second embodiment of the present invention, fig. 3 is a control block diagram showing a feedforward control apparatus of a grid-connected inverter according to a third embodiment of the present invention, and fig. 4 is a detailed configuration showing a first voltage obtaining unit included in the feedforward control apparatus of a grid-connected inverter according to the first embodiment of the present invention.
As shown in fig. 1 to 3, the dc voltage input module 100 inputs a dc voltage to the grid-connected inverter 110, and the grid-connected inverter 110 may be an inverter implemented by an IGBT, which may convert the dc voltage into an ac voltage and output the converted voltage to the filter 120, and the filter 120 may output the filtered voltage to the utility grid 3.
The filter 120 is of the "LCL" type, where the capacitance voltage is the capacitance voltage of the capacitor C of the LCL type filter, and the "LCL type" filter can be a filter passing through two inductors (L1And L2) And a capacitor C, and may also be referred to as a filter that may be equivalently formed of two inductors and one capacitor.
Using the capacitive voltage u of a capacitor according to an embodiment of the inventioncFeed-forward rather than on the basis of the grid-connected point voltage upccFeed forward is performed and therefore sampling of the voltage is relatively easy. For example, for inductor L2(the inductance near the grid-connected point in the LCL type filter) is a system of leakage inductance of the transformer, and the grid-connected point voltage is difficult to sample.
The feedforward control method and the feedforward control device of the grid-connected inverter according to the embodiment of the invention can be used for generating the feedforward voltage control component ufAnd the method can be used for performing feed-forward control on the grid-connected inverter 110.
The feedforward control apparatus of the grid-connected inverter of the present invention may include a first voltage obtaining unit 141 and a first filtering unit 142 as a part of the feedforward voltage control component generating unit 140, and a first adder 145. The feed-forward control apparatus of the grid-connected inverter of the present invention may further include a first scaling unit 143 and a second scaling unit 144 as a part of the feed-forward voltage control component generating unit 140, and may further include a feed-forward control unit (not shown) controlling the grid-connected inverter based on the feed-forward voltage control component.
The feedforward control device of the grid-connected inverter according to the embodiment of the present invention may further include a phase-locked loop 170, and the phase-locked loop 170 may obtain the capacitor voltage ucAnd may be a synchronous phase locked loop or the like.
The first voltage obtaining unit 141 may be based on a capacitance voltage u of a capacitor C in the filter 120 connected to an output terminal of the grid-connected invertercObtain a first voltage ucf2。
As shown in fig. 1 to 3, the first voltage obtaining unit 141 may be implemented by applying a capacitance voltageLine conversion and/or filtering to obtain a first voltage ucf2First voltage ucf2May comprise the fundamental voltage of the capacitor voltage.
In addition, as shown in fig. 1 to 3, the first filtering unit 142 may filter the capacitor voltage u bycFiltering to obtain a second voltage ucf1Specifically, the first filtering unit 142 may filter the capacitor voltage ucPerforming a band-pass filtering in a first frequency band to obtain a second voltage ucf1。
As shown in fig. 1, the first voltage obtaining unit 141 may include two coordinate converting units and a low pass filtering unit 146. The first voltage obtaining unit may obtain the first voltage u by performing coordinate transformation and filtering on the capacitor voltagecf2For example, the first voltage obtaining unit 141 may pair the capacitor voltage u based on the phase angle obtained via the phase locked loop 170cPerforming rotation coordinate conversion, performing low-pass filtering on the capacitor voltage through the low-pass filtering unit 146 under a rotation coordinate system, and performing inverse rotation coordinate conversion on the filtered voltage to obtain a first voltage ucf2。
As shown in fig. 4, the first voltage obtaining unit 141 may perform both positive sequence conversion and negative sequence conversion, and particularly, the first voltage obtaining unit 141 may perform conversion on the capacitance voltage ucTaking positive sequence abc coordinates to dq+The coordinates are transformed, low-pass filtered by a low-pass filtering unit 146, and the filtered voltage is dq+Conversion of coordinates to abc coordinates. Similarly, the first voltage obtaining unit 141 may simultaneously apply the capacitor voltage ucPerforming negative sequence abc coordinates to dq-The coordinates are transformed and then low-pass filtered by a low-pass filtering unit 146, and the filtered voltage is dq-filtered-Converting the coordinate to abc coordinate, and superposing to obtain a first voltage ucf2。
Alternatively, the negative sequence conversion may be omitted, and when the first voltage obtaining unit 141 performs the positive sequence conversion and the negative sequence conversion at the same time, the fundamental voltage component may be accurately obtained.
As shown in fig. 2, unlike the first embodiment according to the present invention, in the second embodiment of the present invention, the first voltage obtaining unit 141 mayBy means of a voltage u across a capacitorcPerforming a Fast Fourier Transform (FFT) to obtain a first voltage ucf2When the first voltage u is obtained by performing FFT on the capacitor voltagecf2And meanwhile, the calculation amount is large, the conversion time is long, and the requirements on the running speed of a software algorithm and/or hardware configuration are high.
As shown in fig. 3, unlike both the first and second embodiments according to the present invention, in the third embodiment of the present invention, the first voltage obtaining unit 141 may obtain the capacitance voltage ucPerforming band-pass filtering in a second frequency band to obtain a first voltage ucf2。
The second frequency band is narrower than the first frequency band, unlike the first frequency band-pass filtered by the first filtering unit 142.
As described above, the first filtering unit 142 may filter the capacitor voltage u bycPerforming a band-pass filtering in a first frequency band to obtain a second voltage ucf1。
The transfer function of the band pass filter of the first filtering unit 142 may be
Figure BDA0002836138630000061
Wherein, ω is0Is the center frequency, optionally the center frequency may be 1250Hz, and the center frequency may be the resonant frequency, ω, of the filter 120cFor example, the bandwidth may be 800 Hz.
The feedforward control device of the grid-connected inverter according to the embodiment of the present invention may band-pass filter the capacitor voltage through the first filtering unit 142, so as to extract a specific component of the capacitor voltage (e.g., 850 Hz-1650 Hz), and further may superimpose (e.g., weight-superimpose) it on the fundamental voltage component obtained by the first voltage obtaining unit, and thus, the feedforward control method according to the embodiment of the present invention may suppress both low-frequency harmonics and have a resonance frequency band damping effect.
In addition, compared with the technical scheme that the feedforward control component is obtained only through coordinate conversion, according to the feedforward control device of the grid-connected inverter and the feedforward control method to be described below, the frequency component in the resonance frequency range of the capacitor voltage can be reserved, the phase margin can be improved more, the control precision is higher, the current harmonic of the power grid is smaller, and the harmonic suppression characteristic is better.
As shown in fig. 1 to 3, the first proportional unit 143 may apply the first voltage ucf2And a first weighting coefficient kf2The first weighted voltage is obtained by multiplication.
The second proportional unit 144 may apply the second voltage ucf1And a second weighting coefficient kf1The multiplication obtains a second weighted voltage.
Alternatively, the first and second scaling units 143 and 144 may be implemented by multipliers and the like. The first adder 145 may add the first weighted voltage and the second weighted voltage to obtain the feedforward voltage control component uf。
First weighting factor kf2And a second weighting coefficient kf1Each of which is in a range of greater than 0 and less than or equal to 1, and optionally, the first weighting coefficient k may be adjusted according to the type of the power grid (e.g., a strong power grid or a weak power grid)f2And a second weighting coefficient kf1The size of (2). Here, the first weighting coefficient k is not necessarily requiredf2And a second weighting coefficient kf1The sum of (a) and (b) is 1, and thus, the feedforward control apparatus and the feedforward control method of the grid-connected inverter according to the embodiment of the invention can have a higher degree of freedom of adjustment.
As shown in fig. 1 to 3, the feed-forward control unit of the grid-connected inverter according to the embodiment of the present invention may further include a current loop 150 and a grid-connected inverter controller 160.
Current loop 150 may be operated using phase angle θ and inductor current i of inductor L11Obtaining a first output voltage uiSpecifically, the input of the current loop 150 may be a preset current irefThe current loop 150 may couple irefThe sine multiplied by theta yields the alternating current i1Then, it is connected with the inductive current i1Taking the difference, the obtained difference of the currents is input to a proportional resonant controller (the transfer function of which can be G)i(s)), further via proportional harmonicsThe vibration controller outputs a first output voltage ui。
The grid-connected inverter controller 160 may include a second adder 161 and a pulse modulation unit 162, and the second adder 161 may control the feedforward voltage component ufAnd a first output voltage uiAre added to output a control voltage u* invThe pulse modulation unit 162 may receive the control voltage u* invAnd outputs a control signal to the grid-connected inverter 110, the pulse modulation unit 162 may receive the control voltage and modulate the control voltage. The pulse modulation unit 162 may be a Space Vector Pulse Width Modulation (SVPWM) unit, etc., but the present invention is not limited thereto.
It should be understood that the respective units or modules in the feedforward control means according to an exemplary embodiment of the invention may be implemented as hardware components and/or software components. Those skilled in the art may implement the various units, for example, using Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), software algorithms, etc., depending on the processing performed by the defined various units.
Fig. 5 and 6 are flowcharts illustrating a feedforward control method of a grid-connected inverter according to an exemplary embodiment of the present invention.
Referring to fig. 5, the feedforward control method of the grid-connected inverter according to the embodiment of the present invention may include steps S110, S120, S130, S140, S150, and S160.
In step S110, a first voltage is obtained based on a capacitance voltage of a capacitor in a filter connected to an output terminal of the grid-connected inverter. As mentioned above, the filter is an LCL type filter.
Here, the first voltage may include a fundamental voltage component of the capacitor voltage, in other words, the weighted feedforward control method according to the embodiment of the present invention has the fundamental voltage component as a weighted term.
As an example, the step S110 of obtaining the first voltage based on the capacitance voltage of the capacitor in the filter connected to the output terminal of the grid-connected inverter may include: the first voltage is obtained by performing a transformation and/or filtering of the capacitor voltage.
As described above, the transformation herein may include at least one of a coordinate transformation and a fast fourier transformation, and the filtering may include at least one of low pass filtering and band pass filtering. When transformed into a coordinate transformation, the coordinate transformation may be conversion of abc coordinates to dq coordinates, or dq coordinates to abc coordinates.
As an example, the step of obtaining the first voltage by performing a transformation and/or filtering on the capacitance voltage may comprise: the first voltage is obtained by performing a fast fourier transform on the capacitor voltage, or by performing a band-pass filtering in a second frequency band on the capacitor voltage, the fast fourier transform being of a known technique and not described in detail here.
In step S120, a second voltage is obtained by filtering the capacitor voltage. The step S120 of obtaining the second voltage by filtering the capacitor voltage may include: the second voltage is obtained by band-pass filtering the capacitor voltage within a first frequency band. The first frequency band may be a frequency band wider than the second frequency band.
According to the feedforward control method of the grid-connected inverter, the band-pass filter can be carried out on the capacitor voltage, so that the specific component of the capacitor voltage is extracted, and then the specific component and the fundamental voltage component can be superposed (for example, weighted superposition), so that the feedforward control method of the grid-connected inverter according to the embodiment of the invention can inhibit low-frequency harmonic waves and has a resonance frequency band damping effect.
In step S130, the first voltage is multiplied by the first weighting coefficient to obtain a first weighted voltage. As described above, the first weighting coefficient may be in a range of greater than 0 and 1 or less.
In step S140, the second voltage is multiplied by the first weighting coefficient to obtain a second weighted voltage. Similarly to the first weighting voltage, the second weighting factor may be in a range of greater than 0 and equal to or less than 1.
In step S150, the first weighted voltage and the second weighted voltage are added to obtain a feedforward voltage control component.
It should be noted that, the steps S110 to S150 may not have a specific sequence, for example, the steps S110 and S120 do not have a sequence, and the step S130 and the step S140 do not have a sequence, in other words, the second voltage may be obtained first and then the first voltage is obtained, the first voltage and the second voltage may also be obtained simultaneously, the first weighted voltage may be obtained first and then the second weighted voltage is obtained, and the first weighted voltage and the second weighted voltage may also be obtained simultaneously.
In step S160, the grid-connected inverter may be controlled based on the feedforward voltage control component.
Referring to fig. 6, controlling the grid-connected inverter based on the feedforward voltage control component may further include steps S1601, S1602, and S1603.
In step S1601, the inductor current of the inductor is obtained. For example, the inductive current, the capacitive voltage, etc. may be obtained by auxiliary means such as a sampling unit (e.g., a sensor).
Step S1601 may be performed simultaneously with step S110 and step S120, or may be performed before or after step S110 and step S120.
In step S1602, a first output voltage is obtained according to the inductor current and the phase angle. For example, the first output voltage may be obtained through a current loop, and the detailed configuration or implementation of the current loop may be as described above and will not be described herein.
In step S1603, the pulse modulation unit of the grid-connected inverter is controlled based on the sum of the feedforward voltage control component and the first output voltage. As described above, the control voltage may be received by the pulse modulation unit as the SVPWM unit and the control signal may be output to the grid-connected inverter.
Fig. 7 is an analysis diagram of a capacitance voltage grid-connected current harmonic, fig. 8 is an analysis diagram of a capacitance voltage weighted feedforward grid-connected current harmonic, and fig. 9 is a comparison diagram of amplitude-frequency and phase-frequency characteristic curves of grid-connected inverter output impedance corresponding to the capacitance voltage feedforward and the capacitance voltage weighted feedforward.
As shown in fig. 7 and 8, when the capacitor voltage is directly feedforward controlled, the total harmonic distortion is about 3.71%; when the capacitor voltage is weighted by feed forward control, the total harmonic distortion is about 1.67%.
The total harmonic distortion is relatively lower when the capacitor voltage is weighted feed forward controlled than when the capacitor voltage is directly feed forward controlled.
As shown in fig. 9, compared with the capacitor voltage direct feedforward, the capacitor voltage weighted feedforward control scheme has a larger phase stability margin and a better effect of suppressing the current harmonics.
In addition, compared with the scheme of performing feedforward on the grid-connected voltage, the phase stability margin of the capacitor voltage weighted feedforward is larger, and the capacitor voltage is easier to sample compared with the grid-connected voltage.
According to the feedforward control device and the feedforward control method of the grid-connected inverter, disclosed by the embodiment of the invention, the current harmonic of a grid-connected point can be inhibited, and the robust stability of a system to the impedance of a power grid is improved.
Compared with the technical scheme of obtaining the feedforward control component only through coordinate conversion, the feedforward control method and the feedforward control method of the grid-connected inverter according to the embodiment of the invention can reserve the frequency component in the resonant frequency range of the capacitor voltage, improve more phase stability margin of the system, improve higher control precision, reduce current harmonic of a power grid and have better harmonic suppression characteristic.
The respective operations of the above-described steps may be written as software programs or instructions, and thus, the feedforward control method according to the exemplary embodiment of the present invention may be implemented via software, and the computer-readable storage medium of the exemplary embodiment of the present invention may store a computer program that, when executed by a processor, implements the feedforward control method of the grid-connected inverter as described in the above exemplary embodiment.
According to various embodiments of the present disclosure, an apparatus (e.g., a module or their functions) or a method may be implemented by a program or instructions stored in a computer-readable storage medium. In the case where the instruction is executed by a processor, the processor may perform a function corresponding to the instruction or perform a method corresponding to the instruction. At least a portion of the modules may be implemented (e.g., executed) by a processor. At least a portion of the programming modules may include modules, programs, routines, instruction sets, and procedures for performing at least one function. In one example, the instructions or software include machine code that is directly executed by one or more processors or computers (such as machine code produced by a compiler). In another example, the instructions or software comprise higher level code that is executed by one or more processors or computers using an interpreter. The instructions or software may be written in any programming language based on the block diagrams and flow diagrams illustrated in the figures and the corresponding description in the specification.
Computer readable storage media include magnetic media such as floppy disks and magnetic tapes, optical media including Compact Disc (CD) ROMs and DVD ROMs, magneto-optical media such as floppy disks, hardware devices such as ROMs, RAMs, and flash memories designed to store and execute program commands. The program command includes a language code executable by a computer using an interpreter and a machine language code generated by a compiler. The hardware devices described above may be implemented by one or more software modules for performing the operations of the various embodiments of the present disclosure.
A module or programming module of the present disclosure may include at least one of the foregoing components with some components omitted or other components added. Operations of the modules, programming modules, or other components may be performed sequentially, in parallel, in a loop, or heuristically. Further, some operations may be performed in a different order, may be omitted, or expanded with other operations.
The computer readable storage medium and/or the feed forward control means of the exemplary embodiments of the present invention may be part of a wind park, or part of a controller or control system, or part of a wind power converter.
For example, according to an exemplary embodiment of the present invention, there may be provided a controller of a grid-connected inverter, the controller may include: a processor (not shown) and a memory (not shown), wherein the memory stores a computer program which, when executed by the processor, implements the feed-forward control method of the grid-connected inverter as described in the above exemplary embodiments.
Although a few exemplary embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments, for example, in which features of different embodiments may be combined, without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims (14)

1. A feedforward control method of a grid-connected inverter is characterized by comprising the following steps:
obtaining a first voltage based on a capacitance voltage of a capacitor in a filter connected to an output terminal of the grid-connected inverter;
obtaining a second voltage by filtering the capacitor voltage;
multiplying the first voltage by a first weighting coefficient to obtain a first weighted voltage;
multiplying the second voltage by a second weighting coefficient to obtain a second weighted voltage;
adding the first weighted voltage and the second weighted voltage to obtain a feedforward voltage control component;
and controlling the grid-connected inverter based on the feedforward voltage control component.
2. The feedforward control method of the grid-connected inverter according to claim 1, wherein the step of obtaining the second voltage by filtering the capacitor voltage includes: the second voltage is obtained by band-pass filtering the capacitor voltage within a first frequency band.
3. The feedforward control method of the grid-connected inverter according to claim 1 or 2, wherein the step of obtaining the first voltage based on a capacitance voltage of a capacitor in a filter connected to the output terminal of the grid-connected inverter includes:
obtaining a first voltage by performing a transformation and/or filtering on the capacitance voltage, wherein the first voltage comprises a fundamental voltage component of the capacitance voltage.
4. A feed-forward control method of a grid-connected inverter according to claim 3, wherein the step of obtaining the first voltage by performing conversion and/or filtering on the capacitor voltage comprises:
obtaining a first voltage by performing a fast Fourier transform on the capacitor voltage or band pass filtering the capacitor voltage within a second frequency band, wherein the first frequency band is wider than the second frequency band.
5. The feedforward control method of the grid-connected inverter according to claim 3, further comprising: the phase angle of the voltage of the capacitor is obtained,
the step of obtaining a first voltage by performing a transformation and/or filtering of the capacitance voltage comprises:
and performing rotation coordinate conversion on the capacitor voltage based on the phase angle, performing low-pass filtering on the capacitor voltage under a rotation coordinate system, and performing rotation coordinate inverse conversion on the filtered voltage to obtain a first voltage.
6. The feedforward control method of the grid-connected inverter according to claim 5, wherein controlling the grid-connected inverter based on the feedforward voltage control component includes:
obtaining an inductor current flowing through an inductor in the filter;
obtaining a first output voltage according to the inductive current and the phase angle; and
and a pulse modulation unit for controlling the grid-connected inverter based on the sum of the feedforward voltage control component and the first output voltage.
7. A computer-readable storage medium characterized in that the computer-readable storage medium stores an instruction or a program which, when executed by a processor, implements the feedforward control method according to any one of claims 1 to 6.
8. A feedforward control device of a grid-connected inverter is characterized by comprising:
a first voltage obtaining unit (141) configured to obtain a first voltage based on a capacitance voltage of a capacitor in a filter connected to an output terminal of the grid-connected inverter;
a first filtering unit (142) configured to obtain a second voltage by filtering the capacitor voltage;
a first scaling unit (143) configured to multiply the first voltage with a first weighting coefficient to obtain a first weighted voltage;
a second scaling unit (144) configured to multiply the second voltage with a second weighting coefficient to obtain a second weighted voltage;
a first adder (145) configured to add the first weighted voltage and the second weighted voltage to obtain a feedforward voltage control component;
and the feedforward control unit is used for controlling the grid-connected inverter based on the feedforward voltage control component.
9. The feed-forward control device of a grid-connected inverter according to claim 8, characterized in that the first filtering unit (142) is configured to obtain the second voltage by band-pass filtering the capacitor voltage within a first frequency band.
10. Feed-forward control device of a grid-connected inverter according to claim 8 or 9, characterized in that the first voltage obtaining unit (141) is further configured to obtain a first voltage by performing transformation and/or filtering on the capacitor voltage, wherein the first voltage comprises a fundamental voltage of the capacitor voltage.
11. The feedforward control apparatus of a grid-connected inverter according to claim 10, wherein the first voltage obtaining unit (141) is further configured to obtain the first voltage by performing a fast fourier transform on the capacitance voltage or by band-pass filtering the capacitance voltage in a second frequency band, wherein the first frequency band is wider than the second frequency band.
12. The feedforward control apparatus of a grid-connected inverter according to claim 10, wherein the feedforward control apparatus further includes a phase-locked loop (170) configured to obtain a phase angle of the capacitor voltage, and the first voltage obtaining unit (141) is further configured to: and performing rotation coordinate conversion on the capacitor voltage based on the phase angle, performing low-pass filtering on the capacitor voltage under a rotation coordinate system, and performing rotation coordinate inverse conversion on the filtered voltage to obtain a first voltage.
13. The feedforward control apparatus of a grid-tied inverter according to claim 12, wherein the feedforward control unit further includes a current loop (150) and a grid-tied inverter controller (160), the current loop (150) is configured to obtain a first output voltage by using the phase angle and an inductive current flowing through an inductor in the filter, the grid-tied inverter controller (160) includes:
a second adder (161) configured to add the feedforward voltage control component and the first output voltage to an output control voltage; and
a pulse modulation unit (162) configured to receive the control voltage and to modulate according to the control voltage.
14. A wind park comprising a feed-forward control arrangement according to any one of claims 8 to 13.
CN202011477703.5A 2020-12-15 2020-12-15 Feedforward control method and device of grid-connected inverter, medium and wind generating set Pending CN114640123A (en)

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