WO2022127268A1 - 风力发电机组、并网逆变器及其前馈控制方法与装置 - Google Patents

风力发电机组、并网逆变器及其前馈控制方法与装置 Download PDF

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Publication number
WO2022127268A1
WO2022127268A1 PCT/CN2021/120968 CN2021120968W WO2022127268A1 WO 2022127268 A1 WO2022127268 A1 WO 2022127268A1 CN 2021120968 W CN2021120968 W CN 2021120968W WO 2022127268 A1 WO2022127268 A1 WO 2022127268A1
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Prior art keywords
voltage
grid
harmonic
feedforward
component
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PCT/CN2021/120968
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English (en)
French (fr)
Inventor
刘佳亮
阮景锋
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新疆金风科技股份有限公司
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Publication of WO2022127268A1 publication Critical patent/WO2022127268A1/zh

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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
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

Definitions

  • the present disclosure generally relates to the field of grid-connected inverters, and more particularly, to a feedforward control method and device for a wind power generator set and a grid-connected inverter.
  • band-pass filters are used to extract harmonics near the resonant frequency in the voltage.
  • the last inductance of the grid-side filter generally uses the leakage inductance of the box change, and its inductance value will change.
  • the strength of the power grid is also different.
  • the lines connected to the grid are different.
  • the same It affects the impedance of the line, so it will indirectly lead to the deviation of the grid-side resonance point of the actual converter from the design value, that is, the resonance point is dynamically changed on the basis of the design value, which will suppress the resonance of the active damping strategy. effect adversely affects.
  • One of the objectives of the exemplary embodiments of the present disclosure is to provide a wind turbine generator, a grid-connected inverter, a feedforward control method and a feedforward control device thereof capable of improving the suppression effect of an active damping strategy for resonance.
  • a feedforward control method of a grid-connected inverter may include: obtaining a capacitance voltage from a capacitor in a filter connected to an output end of the grid-connected inverter from a capacitance voltage Extracting the harmonic signal in the first predetermined frequency range; determining the frequency corresponding to the maximum value of the harmonic amplitude based on the harmonic amplitude of each frequency of the harmonic signal in the first predetermined frequency range; The harmonic voltage component is obtained by band-pass filtering with frequency as the center frequency; the feedforward voltage control component is obtained based on the fundamental voltage component and harmonic voltage component of the capacitor voltage.
  • a computer-readable storage medium where instructions or programs are stored in the computer-readable storage medium, and the above-mentioned feedforward control method can be implemented when the instructions or programs are executed by a processor.
  • a feedforward control device of a grid-connected inverter comprising: a signal extraction unit configured to extract from a filter connected to an output end of the grid-connected inverter The capacitance voltage of the capacitor in extracts the harmonic signal in the first predetermined frequency range; the frequency determination unit is configured to determine and harmonic amplitude based on the harmonic amplitude of each frequency of the harmonic signal in the first predetermined frequency range The frequency corresponding to the maximum value of The fundamental voltage component and harmonic voltage component of , obtain the feedforward voltage control component.
  • a grid-connected inverter including the feedforward control device of the grid-connected inverter.
  • a wind power generating set including the grid-connected inverter.
  • the detection and sampling of the capacitor voltage is easier, and the robustness and stability of the system to the grid impedance are high.
  • FIG. 1 is a control block diagram illustrating a feedforward control device of a grid-connected inverter according to a first embodiment of the present disclosure
  • FIG. 2 is a control block diagram illustrating a feedforward control device of a grid-connected inverter according to a second embodiment of the present disclosure
  • FIG. 3 is a control block diagram illustrating a feedforward control device of a grid-connected inverter according to a third embodiment of the present disclosure
  • FIG. 4 is a diagram showing a detailed configuration of a first voltage obtaining unit included in the feedforward control apparatus of the grid-connected inverter of the first embodiment of the present disclosure.
  • FIG. 5 is a flowchart illustrating a feedforward control method of a grid-connected inverter according to an exemplary embodiment of the present disclosure
  • FIG. 6 is a flowchart illustrating a feedforward control method of a grid-connected inverter according to an exemplary embodiment of the present disclosure.
  • Figure 7 is an analysis diagram of the grid-connected current harmonics when the capacitor voltage is fed forward
  • FIG. 8 is an analysis diagram of grid-connected current harmonics when the capacitor voltage is weighted feed-forward.
  • FIG. 9 is a comparison diagram of the 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.
  • the feedforward control method and feedforward control device for a grid-connected inverter may be applicable to grid-connected inverters in the field of wind power, but are not limited thereto.
  • the center frequency of the band-pass filter is always maintained by is the resonant frequency of the grid-side filter, thereby improving the suppression effect of the active damping strategy on resonance.
  • Active damping here refers to the use of control strategies to suppress the resonance phenomenon.
  • the control strategy of weighted feedforward of capacitor voltage is used to reduce the current harmonics at the grid connection point and improve the phase stability margin of the system.
  • the harmonic voltage component is obtained by band-pass filtering the capacitor voltage
  • the feedforward control component is obtained by superimposing (eg, weighted superposition) with the fundamental voltage component.
  • the feedforward control device and feedforward control method of the present disclosure can obtain higher phase stability margin and lower total harmonic distortion.
  • FIG. 1 is a control block diagram illustrating a feedforward control device of a grid-connected inverter according to a first embodiment of the present disclosure
  • FIG. 2 is a control block diagram illustrating a feedforward of the grid-connected inverter according to a second embodiment of the present disclosure.
  • a control block diagram of the control device FIG. 3 is a control block diagram illustrating a feedforward control device of a grid-connected inverter according to a third embodiment of the present disclosure
  • FIG. 4 is a control block diagram illustrating a grid-connected inverter of the first embodiment of the present disclosure.
  • the DC voltage input module 100 inputs a DC voltage to the grid-connected inverter 110
  • the grid-connected inverter 110 may be an inverter implemented by IGBTs, which can convert the DC voltage into an AC voltage And the converted voltage is output to the filter 120 , and the filter 120 can output the filtered voltage to the grid 130 .
  • the filter 120 may be an "LCL” type filter, where the capacitance voltage refers to the capacitance voltage of the capacitor C of the LCL type filter, and the "LCL type” filter may refer to the two inductors ( L1 and L2) and A filter formed by a capacitor C can also refer to a filter that can be equivalent to two inductors and a capacitor.
  • the inductance value or equivalent inductance value of the last inductor L2 may change due to various reasons, resulting in a change in the resonant frequency of the filter, thereby affecting the effect of the active damping strategy on resonance suppression.
  • the feedforward is performed using the capacitance voltage uc of the capacitor instead of the feedforward based on the grid connection point voltage u pcc , so the sampling of the voltage is relatively easy.
  • the inductor L 2 the inductance close to the grid connection point in the LCL type filter
  • the feed-forward control method and feed-forward control device of a grid-connected inverter can be used to generate harmonic voltage components, and can be further used to generate a feed-forward voltage control component uf , which can be used for grid-connected inverters.
  • the inverter 110 performs feedforward control.
  • the feedforward control apparatus of the grid-connected inverter of the present disclosure may include: a signal extraction unit 148, a frequency determination unit 147, a bandpass filter 142, and a feedforward voltage control component acquisition unit.
  • the signal extraction unit 148 may extract the harmonic signal in the first predetermined frequency range from the capacitance voltage of the capacitor in the filter connected to the output terminal of the grid-connected inverter.
  • the first predetermined frequency range here preferably includes the predetermined center frequency of the bandpass filter.
  • the first predetermined frequency range is (f ⁇ f N , f+f N ), where f is a preset center frequency of the bandpass filter, and f N can be selected according to actual conditions.
  • the signal extraction unit 148 may perform a discrete Fourier transform (eg, a fast Fourier transform) on the capacitor voltage to extract harmonic signals within the first predetermined frequency range.
  • a discrete Fourier transform eg, a fast Fourier transform
  • the signal extraction unit 148 may perform the following processing:
  • the range of n is 0 to N-1
  • x 0 represents the first point of the capacitor voltage signal
  • x 1 represents the second point of the capacitor voltage signal
  • the value range of k is 0 to N- 1
  • X k is the transformed data.
  • Equation (1) can then be transformed using Euler's formula, for example, assuming:
  • the signal extraction unit 148 can extract harmonic signals within a predetermined frequency range. That is, the signal extraction unit 148 may perform FFT on the capacitance voltage data to extract harmonic signals within the first predetermined frequency range.
  • the frequency determination unit 147 may determine the frequency corresponding to the maximum value of the harmonic amplitudes based on the harmonic amplitudes of the respective frequencies of the harmonic signal within the first predetermined frequency range. For example, the frequency determination unit 147 may convert the discrete Fourier transformed data into a complex number form, calculate a modulus value, and determine a maximum value among the modulus values and a frequency corresponding to the maximum value.
  • the frequency determination unit 147 can use formula (3) and formula (4) to convert the transformed data X k into the following complex form:
  • the frequency determination unit 147 can calculate the modulo value of the corresponding frequency based on the above formula (5) And compare the amplitude values in a frequency range, determine the maximum value of the modulo value, and determine the frequency corresponding to the maximum value, thereby determining the center frequency of the band-pass filter.
  • the frequency determination unit 147 may include a band-pass filter design unit, and the center frequency may be determined by the band-pass filter design unit.
  • the band-pass filter 142 can obtain harmonic voltage components by band-pass filtering the capacitor voltage with the frequency corresponding to the maximum value as the center frequency.
  • the bandpass filter 142 may obtain harmonic voltage components by bandpass filtering the capacitor voltage centered on the frequency in response to the voltage magnitude of the capacitor voltage at the frequency corresponding to the maximum value exceeding a threshold.
  • the start-stop mechanism of the bandpass filter 142 may be omitted based on the harmonic conditions of the grid. For example, when the harmonic components of the power grid are small, the band-pass filter 142 may not have a start-stop mechanism, and directly perform the determination of the center frequency, resonance suppression, and the like.
  • the feedforward voltage control component obtaining unit may obtain the feedforward voltage control component based on the fundamental voltage component and the harmonic voltage component of the capacitor voltage.
  • the feedforward voltage control component obtaining unit may include a first voltage obtaining unit 141 .
  • the first voltage obtaining unit 141 may obtain the first voltage u cf2 (ie, the fundamental wave voltage component) based on the capacitance voltage uc of the capacitor C in the filter 120 connected to the output terminal of the grid-connected inverter.
  • the first voltage obtaining unit 141 may obtain the first voltage u cf2 by performing transformation and/or filtering on the capacitor voltage.
  • the band-pass filter 142 obtains the second voltage u cf1 (ie, the harmonic voltage component) by band-pass filtering the capacitor voltage uc .
  • the first voltage obtaining unit 141 may include two coordinate conversion units and a low-pass filtering unit 146 .
  • the first voltage obtaining unit may obtain the first voltage u cf2 by performing coordinate transformation and filtering on the capacitor voltage, for example, the first voltage obtaining unit 141 may rotate the coordinates of the capacitor voltage uc based on the phase angle obtained through the phase-locked loop 170 For conversion, the capacitor voltage is subjected to low-pass filtering by the low-pass filtering unit 146 in the rotating coordinate system, and the rotating coordinate inverse transformation is performed on the filtered voltage to obtain the first voltage u cf2 .
  • the first voltage obtaining unit 141 can perform both positive-sequence transformation and negative-sequence transformation. Specifically, the first voltage obtaining unit 141 can transform the capacitor voltage uc from positive sequence abc coordinates to dq + coordinates , and then low-pass filtering is performed by the low-pass filtering unit 146 , and then the filtered voltage is converted from dq + coordinates to abc coordinates. Similarly, the first voltage obtaining unit 141 can simultaneously convert the negative sequence abc coordinate to dq - coordinate of the capacitor voltage uc , and then perform low-pass filtering through the low-pass filtering unit 146, and perform dq-coordinate to dq - coordinate to the filtered voltage. The transformation of the abc coordinates, the first voltage u cf2 is obtained after superposition.
  • the negative-sequence transformation may be omitted, and when the first voltage obtaining unit 141 performs the positive-sequence transformation and the negative-sequence transformation at the same time, the fundamental wave voltage component can be accurately obtained.
  • the first voltage obtaining unit 141 may perform a fast Fourier transform (FFT) on the capacitance voltage uc to obtain Obtain the first voltage u cf2 (fundamental wave voltage component), when the first voltage u cf2 is obtained by performing FFT on the capacitor voltage, the amount of calculation is large, the transformation time is long, and the running speed of the software algorithm and/or hardware configuration requirements relatively high.
  • FFT fast Fourier transform
  • the first voltage obtaining unit 141 may perform the capacitor voltage uc within the second frequency band. Band-pass filtering to obtain the first voltage ucf2.
  • the first voltage obtaining unit 141 is implemented by a band-pass filter, its transfer function G f (s) is not particularly limited.
  • the second frequency band is narrower than the first frequency band.
  • the band-pass filter 142 can obtain the second voltage u cf1 by band-pass filtering the capacitor voltage uc in the first frequency band .
  • the transfer function of the bandpass filter of bandpass filter 142 may be:
  • ⁇ 0 is the center frequency
  • the center frequency can be adjusted to be 1250 Hz
  • the center frequency can be the resonant frequency of the filter 120
  • ⁇ c is the bandwidth, for example, the bandwidth can be 800 Hz.
  • the fundamental wave voltage component can also be obtained by Hilbert transform or the like.
  • the feedforward control device of the grid-connected inverter can band-pass filter the capacitor voltage through the band-pass filter 142, so as to extract the harmonic voltage component of the capacitor voltage, and then can compare it with the capacitor voltage through the first
  • the fundamental wave voltage components obtained by the voltage obtaining unit are superimposed (eg, weighted superposition), so the feedforward control method according to the embodiment of the present disclosure can not only suppress low-frequency harmonics, but also have a resonance frequency band damping effect.
  • the capacitance voltage can be preserved.
  • the phase margin can be improved more, the control accuracy is higher, the current harmonics of the grid are smaller, and the harmonic suppression characteristics are better.
  • the feedforward voltage control component obtaining unit may further include: a first proportional unit 143 , a second proportional unit 144 and a first adder 145 .
  • the feedforward voltage control component acquisition unit may also not include weighted feedforward components such as a proportional unit and an adder.
  • the first proportional unit 143 may multiply the first voltage u cf2 by the first weighting coefficient k f2 to obtain the first weighted voltage.
  • the second proportional unit 144 may multiply the second voltage u cf1 by the second weighting coefficient k f1 to obtain a second weighted voltage.
  • both the first proportional unit 143 and the second proportional unit 144 can be implemented by a multiplier or the like.
  • the first summer 145 may add the first weighted voltage and the second weighted voltage to obtain the feedforward voltage control component uf .
  • Both the first weighting coefficient k f2 and the second weighting coefficient k f1 can be in the range of greater than 0 and less than or equal to 1.
  • the first weighting coefficient k can be adjusted according to the type of the power grid (for example, a strong power grid or a weak power grid).
  • the size of f2 and the second weighting coefficient k f1 are not necessarily required to be 1, and therefore, the feedforward control apparatus and feedforward control method of the grid-connected inverter according to the embodiments of the present disclosure may have higher freedom of adjustment.
  • the feedforward control apparatus for a grid-connected inverter may further include a current loop 150 and a grid-connected inverter controller 160 .
  • the current loop 150 can obtain the first output voltage ui by using the phase angle ⁇ and the inductor current i 1 of the inductor L1.
  • the input of the current loop 150 can be a preset current i ref
  • the current loop 150 can convert the i ref is multiplied by the sine of ⁇ to obtain the AC current i 1 *, which is then differentiated with the inductor current i 1 , and the difference of the obtained currents is input to the proportional resonant controller (the transfer function of which can be G i (s)), and then via The output of the proportional resonance controller obtains the 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 add the feedforward voltage control component uf and the first output voltage ui to output a control voltage u * inv , the pulse modulation unit 162 may receive the control voltage u * inv and output a control signal to the grid-tied inverter 110 .
  • the pulse modulation unit 162 may be a space vector pulse width modulation (SVPWM) unit or the like, but the present disclosure is not limited thereto.
  • each unit or module in the feedforward control apparatus may be implemented as hardware components and/or software components.
  • Those skilled in the art can implement each unit by using, for example, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a software algorithm, or the like according to the defined processing performed by each unit.
  • FPGA Field Programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • 5 and 6 are flowcharts illustrating a feedforward control method of a grid-connected inverter according to an exemplary embodiment of the present disclosure.
  • the feedforward control method for a grid-connected inverter may include steps S110 , S120 , S130 and S140 .
  • a harmonic signal in a first predetermined frequency range is extracted from the capacitance voltage of the capacitor in the filter connected to the output end of the grid-connected inverter.
  • the filter may be an LCL type filter.
  • the first predetermined frequency range preferably includes a predetermined center frequency for band pass filtering.
  • Harmonic signals can be extracted by means of discrete Fourier analysis.
  • the step S110 of extracting the harmonic signal in the first predetermined frequency range from the capacitor voltage of the capacitor in the filter connected to the output end of the grid-connected inverter may include: performing discrete Fourier analysis on the capacitor voltage to obtain Harmonic signals within a first predetermined frequency range are extracted.
  • the specific discrete Fourier analysis process can be as described above, that is, the harmonic signals in the first predetermined range can be extracted by performing discrete Fourier transform (eg, fast Fourier transform) on the capacitor voltage.
  • discrete Fourier transform eg, fast Fourier transform
  • the frequency corresponding to the maximum value of the harmonic amplitude may be determined based on the harmonic amplitude of each frequency of the harmonic signal in the first predetermined frequency range.
  • the step S120 of determining the frequency corresponding to the maximum value of the harmonic amplitude based on the harmonic amplitude of each frequency of the harmonic signal in the first predetermined frequency range may include: converting the discrete Fourier transformed data into a complex form , the modulo value is calculated, and the maximum value among the modulo values and the frequency corresponding to the maximum value are determined.
  • the transformed data can be converted into a complex number form, then the modulus value of the corresponding frequency is calculated based on the transformed data in the complex number form, and the amplitude (modulus value) in a frequency range is compared to determine the maximum value in the modulus value, And the frequency corresponding to the maximum value among the modulo values is determined, thereby determining the center frequency of the bandpass filter.
  • step S130 harmonic voltage components are obtained by band-pass filtering the capacitor voltage with the frequency corresponding to the maximum value as the center frequency.
  • the specific transfer function and the like of the band-pass filtering are as described above, and will not be repeated here.
  • step S140 a feedforward voltage control component is obtained based on the fundamental voltage component and the harmonic voltage component of the capacitor voltage.
  • the band-pass filtering may have a start-stop mechanism
  • the step S130 of obtaining the harmonic voltage component by performing band-pass filtering on the capacitor voltage with the frequency as the center frequency may include: in response to the capacitor voltage being at a value corresponding to the maximum amplitude value The voltage amplitude of the frequency exceeds the threshold and the harmonic voltage component is obtained by band-pass filtering the capacitor voltage with the frequency as the center frequency.
  • the specific harmonic components are extracted more accurately for feedforward control, and the performance of the active damping strategy against resonance is improved. Inhibitory effect.
  • the current harmonics at the grid-connected point can also be reduced by means of capacitor-voltage weighted feed-forward, and the stability margin of the system phase angle can be improved.
  • the step S140 of obtaining the feedforward voltage control component based on the fundamental wave voltage component and the harmonic voltage component of the capacitor voltage may include steps S1401 , S1402 and S1403 as weighted feedforward control steps, however, the present disclosure is not limited to Here, the weighted feedforward control is only an example, and the present disclosure is not limited thereto.
  • step S1401 the fundamental wave voltage component is multiplied by a first weighting coefficient to obtain a first weighted voltage.
  • the first weighting coefficient may be in a range greater than 0 and less than or equal to 1.
  • step S1402 the harmonic voltage component is multiplied by a second weighting coefficient to obtain a second weighting voltage. Similar to the first weighting voltage, the second weighting coefficient may also be in a range greater than 0 and less than or equal to 1.
  • step S1403 the first weighted voltage and the second weighted voltage are added to obtain a feedforward voltage control component.
  • the fundamental wave voltage component can be obtained in various ways, for example, coordinate transformation and low-pass filtering, fast Fourier transform, Hilbert transform, band-pass filtering, and the like as described above.
  • the feedforward control method of the present disclosure may further include the step of obtaining the phase angle of the capacitor voltage.
  • the capacitor voltage can be transformed into a rotational coordinate based on the phase angle, the capacitor voltage can be low-pass filtered in the rotating coordinate system, and the filtered voltage can be inversely transformed by the rotational coordinate to obtain the fundamental voltage component.
  • the specific coordinate transformation and low-pass filtering process have been described with reference to FIG. 4 , and will not be repeated here.
  • the feedforward control method for a grid-connected inverter may further include applying a feedforward voltage control component to the output voltage of the current loop, thereby generating a control voltage.
  • the feedforward control method of the present disclosure may include: obtaining an inductor current of an inductor; obtaining a first output voltage through a current loop using the inductor current and a phase angle; and controlling the sum of the component and the first output voltage based on the feedforward voltage
  • the pulse modulation unit is controlled to control the grid-tied inverter.
  • the feedforward control method of the present disclosure can be used for the acquisition of harmonic voltage components, and can also be further used for the acquisition of feedforward voltage control components and the generation of the final control voltage.
  • inductive current, capacitive voltage, etc. may be obtained by auxiliary devices such as sampling units (eg, sensors).
  • the control voltage may be received and output the control signal to the grid-tied inverter through the pulse modulation unit as the SVPWM unit.
  • Figure 7 is the analysis diagram of the capacitor voltage grid-connected current harmonics
  • Figure 8 is the analysis diagram of the capacitor voltage weighted feedforward grid-connected current harmonics
  • Figure 9 is the grid-connected inverse corresponding to the capacitor voltage feedforward and the capacitor voltage weighted feedforward
  • the total harmonic distortion is relatively lower when the capacitor voltage is subjected to weighted feedforward control.
  • the weighted feedforward control scheme of the capacitor voltage has a larger phase stability margin and a better effect of suppressing current harmonics.
  • phase stability margin of the capacitor-voltage weighted feed-forward is larger, and it is relatively easier to sample the capacitor voltage than to sample the grid-connected voltage.
  • the feedforward control method and feedforward control device of a grid-connected inverter according to the embodiments of the present disclosure can improve the suppression effect of the active damping strategy on resonance.
  • the feedforward control device and feedforward control method of the grid-connected inverter according to the embodiments of the present disclosure can suppress the current harmonics at the grid-connected point, and improve the robust stability of the system to the grid impedance.
  • the feedforward control method and feedforward control method of the grid-connected inverter can retain the frequency within the resonant frequency range of the capacitor voltage component, the phase stability margin of the system can be improved more, the control accuracy is higher, the current harmonics of the power grid are smaller, and the harmonic suppression characteristics are better.
  • the feedforward control method and feedforward control device of a grid-connected inverter according to the embodiments of the present disclosure can improve the suppression effect of the active damping strategy on resonance.
  • the feedforward control method according to the exemplary embodiment of the present disclosure can be implemented via software, and the computer-readable storage medium of the exemplary embodiment of the present disclosure can store the A computer program, when the computer program is executed by the processor, implements the feedforward control method of the grid-connected inverter according to the above-mentioned exemplary embodiment.
  • apparatuses eg, modules or their functions
  • the processor may perform a function corresponding to the instruction or perform a method corresponding to the instruction.
  • At least a portion of a module may be implemented (eg, executed) by a processor.
  • At least a portion of a programming module may include modules, programs, routines, sets of instructions, and processes for performing at least one function.
  • the instructions or software include machine code (such as machine code produced by a compiler) that is directly executed by one or more processors or computers.
  • the instructions or software include higher level code that is executed by one or more processors or computers using an interpreter. Instructions or software may be written using any programming language based on the block diagrams and flowcharts shown in the drawings and corresponding descriptions in the specification.
  • Computer-readable storage media includes non-transitory computer-readable storage media, which may include, for example, magnetic media such as floppy disks and magnetic tapes, optical media (including compact disk (CD) ROM and DVD ROM), magneto-optical media such as floppy disks, Hardware devices such as ROM, RAM, and flash memory designed to store and execute program commands.
  • the program commands include language code executable by the computer using an interpreter and machine language code generated by a compiler.
  • the above-described hardware devices may be implemented by one or more software modules for performing operations of 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.
  • the operations of the modules, programming modules, or other components may be performed sequentially, in parallel, in a loop, or heuristically. Additionally, some operations may be performed in a different order, omitted, or extended with other operations.
  • the computer readable storage medium and/or the feedforward control device of the exemplary embodiments of the present disclosure may be part of a wind turbine, or a controller or control system, or a wind power converter.
  • exemplary embodiments according to the present disclosure may provide 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
  • the program when the computer program is executed by the processor, implements the feedforward control method of the grid-connected inverter as described in the above-mentioned exemplary embodiments.

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Abstract

本公开提供一种风力发电机组、并网逆变器及其前馈控制方法与装置，该前馈控制方法包括：从与并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号；基于谐波信号在第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率；通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量；基于电容电压的基波电压分量和谐波电压分量获得前馈电压控制分量。

Description

风力发电机组、并网逆变器及其前馈控制方法与装置 技术领域
本公开总体说来涉及并网逆变器领域，更具体地讲，涉及一种风力发电机组、并网逆变器的前馈控制方法与装置。
背景技术
目前，利用网侧交流电压进行网侧谐振抑制是切实可行的方案，为了减少对其它频次谐波产生影响，采用带通滤波器将电压中的谐振频率附近的谐波进行提取。
实际操作中，虽然网侧电抗，网侧滤波器是固定的，但一般网侧滤波器的最后一个电感多利用箱变漏感，其电感值会发生变化。另外，考虑到不同风场线路不同，电网强度也不相同，相同风电场内，即使同一型号的风力发电机组，连接电网线路亦不同，当风场内其它风力发电机组运行状态不同时，同样会影响线路的阻抗，因此会间接的导致实际变流器的网侧谐振点与设计值产生偏差，即谐振点是在设计值的基础上动态变化的，这会对有源阻尼策略对谐振的抑制效果产生不利影响。
上述内容仅作为背景信息呈现，以供了解相关技术内容。上述内容的公开不意味着上述内容为现有技术。
发明内容
本公开的示例性实施例的目的之一在于提供一种能够改善有源阻尼策略针对谐振的抑制效果的风力发电机组、并网逆变器及其前馈控制方法及前馈控制装置。
根据本公开的第一方面，提供一种并网逆变器的前馈控制方法，该前馈控制方法可包括：从与并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号；基于谐波信号在第一预定频率范围内的各个频率的谐波幅值，确定与谐波幅值的最大值对应的频率；通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量；基于电容 电压的基波电压分量和谐波电压分量获得前馈电压控制分量。
根据本公开的第二方面，提供一种计算机可读存储介质，计算机可读存储介质存储有指令或程序，当指令或程序由处理器执行时可实现上述前馈控制方法。
根据本公开的第三方面，提供一种并网逆变器的前馈控制装置，该前馈控制装置包括：信号提取单元，被配置为从与并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号；频率确定单元，被配置为基于谐波信号在第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率；带通滤波器，被配置为通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量；前馈电压控制分量获取单元，被配置为基于电容电压的基波电压分量和谐波电压分量获得前馈电压控制分量。
根据本公开的第四方面，提供一种并网逆变器，包括所述的并网逆变器的前馈控制装置。
根据本公开的第五方面，提供一种风力发电机组，包括所述的并网逆变器。
根据本公开的实施例的并网逆变器的前馈控制装置及前馈控制方法对电容电压的检测采样更加容易，系统对电网阻抗的鲁棒稳定性高。
将在接下来的描述中部分阐述本发明总体构思另外的方面和/或优点，还有一部分通过描述将是清楚的，或者可以经过本发明总体构思的实施而得知。
附图说明
通过下面结合示例性地示出实施例的附图进行的描述，本公开示例性实施例的上述和其他目的和特点将会变得更加清楚，其中：
图1是示出根据本公开的第一实施例的并网逆变器的前馈控制装置的控制框图；
图2是示出根据本公开的第二实施例的并网逆变器的前馈控制装置的控制框图；
图3是示出根据本公开的第三实施例的并网逆变器的前馈控制装置的控制框图；
图4是示出本公开的第一实施例的并网逆变器的前馈控制装置所包括第 一电压获得单元的详细配置。
图5是示出根据本公开的示例性实施例的并网逆变器的前馈控制方法的流程图；
图6是示出根据本公开的示例性实施例的并网逆变器的前馈控制方法的流程图。
图7是电容电压前馈时的并网电流谐波的分析图；
图8是电容电压加权前馈时的并网电流谐波的分析图；以及
图9是与电容电压前馈和电容电压加权前馈对应的并网逆变器输出阻抗幅频和相频特性曲线的对比示图。
具体实施方式
现将详细参照本公开的实施例，实施例的示例在附图中示出，其中，相同的标号始终指的是相同的部件。以下将通过参照附图来说明实施例，以便解释本公开。
根据本公开的实施例的并网逆变器的前馈控制方法和前馈控制装置可以适用于风电领域的并网逆变器，但不限于此。
根据本公开的实施例的并网逆变器的前馈控制方法和前馈控制装置在针对网侧滤波器的电容电压进行前馈控制的过程中，通过使带通滤波器的中心频率始终保持为网侧滤波器的谐振频率，从而改善有源阻尼策略针对谐振的抑制效果。这里的有源阻尼是指利用控制策略抑制谐振现象。
根据本公开的实施例利用电容电压加权前馈这一控制策略来降低并网点的电流谐波，提高系统的相位稳定裕度。再者，根据本公开的实施例通过对电容电压进行带通滤波的方式来获得谐波电压分量，并将其与基波电压分量叠加(例如，加权叠加)来获得前馈控制分量。
与电网电压前馈、电容电压直接前馈等控制策略相比，本公开的前馈控制装置及前馈控制方法能够获得更高的相位稳定裕度，总谐波失真更小。
图1是示出根据本公开的第一实施例的并网逆变器的前馈控制装置的控制框图，图2是示出根据本公开的第二实施例的并网逆变器的前馈控制装置的控制框图，图3是示出根据本公开的第三实施例的并网逆变器的前馈控制装置的控制框图，图4是示出本公开的第一实施例的并网逆变器的前馈控制装置所包括第一电压获得单元的详细配置。
如图1至图3所示，直流电压输入模块100向并网逆变器110输入直流电压，并网逆变器110可以是通过IGBT实现的逆变器，其可将直流电压转换为交流电压并且将转换后的电压输出到滤波器120，滤波器120可以向电网130输出滤波后的电压。
滤波器120可以为“LCL”型滤波器，这里的电容电压是指LCL型滤波器的电容器C的电容电压，“LCL型”滤波器可以指通过两个电感器(L 1和L 2)和一个电容器C形成的滤波器，也可以是指可以等效为两个电感器和一个电容器形成的滤波器。
如上所述，最后一个电感器L 2的电感值或等效电感值可能由于各种原因而导致变化，导致滤波器的谐振频率产生变化，从而影响有源阻尼策略针对谐振的抑制效果。
根据本公开的实施例利用电容器的电容电压u c进行前馈而不是基于并网点电压u pcc进行前馈，因此对电压的采样相对容易。例如，对于电感器L 2(LCL型滤波器中的靠近并网点的电感)为变压器漏感的系统，对并网点电压进行采样较为困难。
根据本公开的实施例的并网逆变器的前馈控制方法和前馈控制装置可用于产生谐波电压分量，并且还可进一步用于产生前馈电压控制分量u f，可用于对并网逆变器110进行前馈控制。
本公开的并网逆变器的前馈控制装置可包括：信号提取单元148、频率确定单元147、带通滤波器142和前馈电压控制分量获取单元。
信号提取单元148可以从与并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号。
这里的第一预定频率范围优选包括带通滤波器的预设中心频率。例如，第一预定频率范围为(f－f N，f+f N)，其中，f为预设的带通滤波器的中心频率，f N可以根据实际情况选取。
例如，信号提取单元148可以对电容电压进行离散傅里叶变换(例如，快速傅里叶变换)以提取在第一预定频率范围内的谐波信号。
具体地，信号提取单元148可执行以下处理：
记录电容电压u c的一段数据x n，数据点数为N，采样频率为f s，利用以下公式进行离散傅里叶变换(例如，快速傅里叶变换)：
Figure PCTCN2021120968-appb-000001
其中，n的范围是0到N-1，x 0表示电容电压信号的第一个点，x 1表示电容电压信号的第二个点，依此类推，k的取值范围是0到N-1，X k为变换后的数据。
然后，可以利用欧拉公式将式(1)进行转换，例如，假设：
Figure PCTCN2021120968-appb-000002
依据欧拉公式，可以得出
Figure PCTCN2021120968-appb-000003
可以得到：
Figure PCTCN2021120968-appb-000004
由此，信号提取单元148可以提取预定频率范围内的谐波信号。也就是说，信号提取单元148可以对电容电压数据执行FFT，以提取第一预定频率范围内的谐波信号。
频率确定单元147可以基于谐波信号在第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率。例如，频率确定单元147可以将离散傅里叶变换后的数据转换为复数形式，计算模值，并且确定模值中的最大值以及与最大值对应的频率。
具体地，频率确定单元147可以利用式(3)和式(4)，将变换后的数据X k转换为以下复数形式：
Z＝a+ib               (5)
频率确定单元147可以基于上式(5)计算对应频率的模值
Figure PCTCN2021120968-appb-000005
并且对比一段频率范围内的幅值，确定模值的最大值，并确定与最大值对应的频率，由此确定带通滤波器的中心频率。频率确定单元147可以包括带通滤波器设计单元，可以由带通滤波器设计单元确定中心频率。
带通滤波器142可通过对电容电压进行以与最大值对应的频率为中心频率的带通滤波来获得谐波电压分量。
作为示例，带通滤波器142可以响应于电容电压在与最大值对应的频率的电压幅值超过阈值而通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量。
带通滤波器142的启停机制可基于电网的谐波情况而被省略。例如，当电网谐波分量较少时，带通滤波器142可以不具有启停机制，而直接进行中 心频率的确定、谐振抑制等。
前馈电压控制分量获取单元可以基于电容电压的基波电压分量和谐波电压分量获得前馈电压控制分量。
具体地，前馈电压控制分量获取单元可以包括第一电压获得单元141。
第一电压获得单元141可以基于与并网逆变器的输出端连接的滤波器120中的电容器C的电容电压u c获得第一电压u cf2(即，基波电压分量)。
如图1至图3所示，第一电压获得单元141可通过对电容电压执行变换和/或滤波来获得第一电压u cf2。
另外，如图1至图3所示，带通滤波器142通过对电容电压u c进行带通滤波以获得第二电压u cf1(即，谐波电压分量)。
如图1所示，第一电压获得单元141可包括两个坐标转换单元以及低通滤波单元146。第一电压获得单元可通过对电容电压执行坐标变换和滤波来获得第一电压u cf2，例如，第一电压获得单元141可基于经由锁相环170获得的相角对电容电压u c进行旋转坐标转换，在旋转坐标系下通过低通滤波单元146对电容电压进行低通滤波，对滤波后的电压进行旋转坐标反变换以获得第一电压u cf2。
如图4所示，第一电压获得单元141可以进行正序变换和负序变换两者，具体地，第一电压获得单元141可以对电容电压u c进行正序abc坐标至dq +坐标的转化，然后通过低通滤波单元146进行低通滤波，再对滤波后的电压进行dq +坐标至abc坐标的转换。类似地，第一电压获得单元141可以同时对电容电压u c进行负序abc坐标至dq -坐标的转化，然后通过低通滤波单元146进行低通滤波，对滤波后的电压进行dq -坐标至abc坐标的转换，叠加后获得第一电压u cf2。
可选地，负序变换可被省略，当第一电压获得单元141同时进行正序转换和负序转换时，可精确地获得基波电压分量。
如图2所示，与根据本公开的第一实施例不同，在本公开的第二实施例中，第一电压获得单元141可通过对电容电压u c执行快速傅里叶变换(FFT)来获得第一电压u cf2(基波电压分量)，当通过对电容电压执行FFT来获得第一电压u cf2时，计算量较大，变换时间较长，对软件算法运行速度和/或硬件配置要求比较高。
如图3所示，与根据本公开的第一实施例和第二实施例均不同，在本公 开的第三实施例中，第一电压获得单元141可对电容电压uc进行第二频带内的带通滤波来获得第一电压ucf2。当第一电压获得单元141通过带通滤波器实现时，其传递函数G f(s)不受具体限制。与通过带通滤波器142进行带通滤波的第一频带不同，第二频带窄于第一频带。
如上所述，带通滤波器142可通过对电容电压u c进行第一频带内的带通滤波以获得第二电压u cf1。
带通滤波器142的带通滤波器的传递函数可以为：
Figure PCTCN2021120968-appb-000006
其中，ω 0为中心频率，可选地，中心频率经过调整可以为1250Hz，并且中心频率可以是滤波器120的谐振频率，ω c为带宽，例如，带宽可以为800Hz。
虽然没有示出，但基波电压分量还可以通过希尔伯特变换等获得。
根据本公开的实施例的并网逆变器的前馈控制装置可通过带通滤波器142对电容电压进行带通滤波，从而提取电容电压的谐波电压分量，进而可以将其与经由第一电压获得单元获得的基波电压分量进行叠加(例如，加权叠加)，因此，根据本公开的实施例的前馈控制方法既能抑制低频谐波，又具有谐振频带阻尼作用。
另外，与仅通过坐标转换获得前馈控制分量的技术方案相比，根据本公开的实施例的并网逆变器的前馈控制装置及下文将描述的前馈控制方法，可保留电容电压的谐振频率范围内的频率分量，相位裕度可改善更多，控制精度更高，电网的电流谐波更小，谐波抑制特性更好。
如图1至图3所示，前馈电压控制分量获取单元还可包括：第一比例单元143、第二比例单元144和第一加法器145。前馈电压控制分量获取单元也可以不包括比例单元、加法器等加权前馈部件。
如图1至图3所示，第一比例单元143可以将第一电压u cf2与第一加权系数k f2相乘来获得第一加权电压。
第二比例单元144可将第二电压u cf1与第二加权系数k f1相乘以获得第二加权电压。
可选地，第一比例单元143和第二比例单元144均可通过乘法器等实现。第一加法器145可以将第一加权电压与第二加权电压相加以获得前馈电压控 制分量u f。
第一加权系数k f2和第二加权系数k f1均可处于大于0且小于等于1的范围内，可选地，可根据电网的类型(例如，强电网或弱电网)调整第一加权系数k f2和第二加权系数k f1的大小。这里，不必要求第一加权系数k f2和第二加权系数k f1的总和为1，因此，根据本公开的实施例的并网逆变器的前馈控制装置和前馈控制方法可具有更高的调整自由度。
如图1至图3所示，根据本公开的实施例的并网逆变器的前馈控制装置还可包括电流环150和并网逆变器控制器160。
电流环150可以通过使用相角θ以及电感器L1的电感电流i 1获得第一输出电压u i，具体地，电流环150的输入可以为预先设定的电流i ref，电流环150可以将i ref乘以θ的正弦获得交流电流i 1*，然后将其与电感电流i 1作差，获得的电流之差输入到比例谐振控制器(其传递函数可以为G i(s))，进而经由比例谐振控制器输出得到第一输出电压u i。
并网逆变器控制器160可包括第二加法器161和脉冲调制单元162，第二加法器161可将前馈电压控制分量u f与第一输出电压u i相加以输出控制电压u * inv，脉冲调制单元162可接收控制电压u * inv并且向并网逆变器110输出控制信号。脉冲调制单元162可以为空间矢量脉宽调制(SVPWM)单元等，但本公开不限与此。
应该理解，根据本公开示例性实施例的前馈控制装置中的各个单元或模块可被实现硬件组件和/或软件组件。本领域技术人员可根据限定的各个单元所执行的处理，可以例如使用现场可编程门阵列(FPGA)、专用集成电路(ASIC)、软件算法等来实现各个单元。
图5和图6是示出根据本公开的示例性实施例的并网逆变器的前馈控制方法的流程图。
参照图5，根据本公开的实施例的并网逆变器的前馈控制方法可包括步骤S110、S120、S130和S140。
在步骤S110中，从与并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号。如上所述，滤波器可以为LCL型滤波器。第一预定频率范围优选包括带通滤波的预设中心频率。
可通过离散傅里叶分析的方式提取谐波信号。
具体地，从与并网逆变器的输出端连接的滤波器中的电容器的电容电压 提取第一预定频率范围内的谐波信号的步骤S110可包括：对电容电压进行离散傅里叶分析以提取在第一预定频率范围内的谐波信号。
具体的离散傅里叶分析的过程可如上所述，即，可以通过对电容电压进行离散傅里叶变换(例如，快速傅里叶变换)来提取第一预定范围内的谐波信号。
在步骤S120，可以基于谐波信号在第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率。
基于谐波信号在第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率的步骤S120可包括：将离散傅里叶变换后的数据转换为复数形式，计算模值，并且确定模值中的最大值以及与最大值对应的频率。
具体地，可以将变换后的数据转换为复数形式，然后基于复数形式的变换数据计算对应频率的模值，并且对比一段频率范围内的幅值(模值)，确定模值中的最大值，并且确定与模值中的最大值对应的频率，由此确定带通滤波器的中心频率。
在步骤S130，通过对电容电压进行以与最大值对应的频率为中心频率的带通滤波来获得谐波电压分量。具体的带通滤波的传递函数等如上所述，这里不再赘述。
在步骤S140，基于电容电压的基波电压分量和谐波电压分量获得前馈电压控制分量。
如上所述，带通滤波可具有启停机制，通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量的步骤S130可包括：响应于电容电压在与幅值最大值对应的频率的电压幅值超过阈值而通过对电容电压进行以频率为中心频率的带通滤波来获得谐波电压分量。
根据本公开的实施例，通过将带通滤波的中心频率始终保持为网侧滤波器的谐振频率，由此更加精确地提取特定谐波分量用于前馈控制，提高有源阻尼策略针对谐振的抑制效果。
另外，根据本公开的实施例，还可通过电容电压加权前馈的方式降低并网点的电流谐波，提高系统相角稳定裕度。
如图6所示，基于电容电压的基波电压分量和谐波电压分量获得前馈电压控制分量的步骤S140可包括作为加权前馈控制步骤的步骤S1401、S1402 和S1403，然而，本公开不限于此，加权前馈控制仅仅是示例，本公开不限于此。
在步骤S1401，将基波电压分量与第一加权系数相乘以获得第一加权电压。第一加权系数可以处于大于0且小于等于1的范围。
在步骤S1402，将谐波电压分量与第二加权系数相乘以获得第二加权电压，与第一加权电压类似，第二加权系数也可以处于大于0且小于等于1的范围。
在步骤S1403，将第一加权电压与第二加权电压相加以获得前馈电压控制分量。
基波电压分量的获取可以有多种方式，例如，如上所述的坐标转换和低通滤波、快速傅里叶变换、希尔伯特变换、带通滤波等等。
这里仅仅以坐标转换和低通滤波的方式描述基波电压分量的获取，不公开不限于此。
例如，本公开的前馈控制方法还可包括获得电容电压的相角的步骤。
具体地，可以基于相角对电容电压进行旋转坐标转换，在旋转坐标系下对电容电压进行低通滤波，对滤波后的电压进行旋转坐标反变换以获得基波电压分量。具体的坐标转换和低通滤波过程已参照图4进行了描述，这里不再赘述。
根据本公开的实施例的并网逆变器的前馈控制方法还可包括将前馈电压控制分量加载到电流环的输出电压上，从而产生控制电压。
具体地，本公开的前馈控制方法可包括：获得电感器的电感电流；通过使用电感电流以及相角的电流环获得第一输出电压；以及基于前馈电压控制分量和第一输出电压之和控制脉冲调制单元以控制并网逆变器。
换言之，本公开的前馈控制方法可用于谐波电压分量的获取，也可以进一步用于前馈电压控制分量的获取以及最终的控制电压的生成。
作为示例，可通过诸如采样单元(例如，传感器)等辅助性装置获得电感电流、电容电压等。可以通过作为SVPWM单元的脉冲调制单元接收控制电压并且向并网逆变器输出控制信号。
图7是电容电压并网电流谐波的分析图，图8是电容电压加权前馈并网电流谐波的分析图，图9是与电容电压前馈和电容电压加权前馈对应的并网逆变器输出阻抗幅频和相频特性曲线的对比示图。
如图7和图8所示，当直接对电容电压进行前馈控制时，总谐波失真约为3.71％；当通过对电容电压进行加权前馈控制时，总谐波失真约为1.67％。
与直接对电容电压进行前馈控制的情况相比，对电容电压进行加权前馈控制时的总谐波失真相对更低。
如图9所示，与电容电压直接前馈相比，电容电压加权前馈控制方案的相位稳定裕度更大，抑制电流谐波的效果更好。
另外，与对并网电压进行前馈的方案相比，电容电压加权前馈的相位稳定裕度更大，并且与对并网电压进行采样相比，对电容电压进行采样相对更加容易。
根据本公开的实施例的并网逆变器的前馈控制方法及前馈控制装置能够提高有源阻尼策略针对谐振的抑制效果。
根据本公开的实施例的并网逆变器的前馈控制装置及前馈控制方法可抑制并网点的电流谐波，提高系统对电网阻抗的鲁棒稳定性。
与仅通过坐标转换获得前馈控制分量的技术方案相比，根据本公开的实施例的并网逆变器的前馈控制方法及前馈控制方法，可保留电容电压的谐振频率范围内的频率分量，系统的相位稳定裕度可改善更多，控制精度更高，电网的电流谐波更小，谐波抑制特性更好。
根据本公开的实施例的并网逆变器的前馈控制方法及前馈控制装置能够提高有源阻尼策略针对谐振的抑制效果。
上述步骤的各个操作可被编写为软件程序或指令，因此，根据本公开的示例性实施例的前馈控制方法可经由软件实现，本公开的示例性实施例的计算机可读存储介质可存储有计算机程序，当所述计算机程序被处理器执行时实现如上述示例性实施例所述的并网逆变器的前馈控制方法。
根据本公开的各个实施例，装置(例如模块或它们的功能)或方法可以通过存储在计算机可读存储介质中的程序或指令来实现。在该指令被处理器执行的情况下，处理器可以执行对应于该指令的功能或执行对应于该指令的方法。模块的至少一部分可以由处理器实现(例如，执行)。编程模块的至少一部分可以包括用于执行至少一个功能的模块、程序、例程、指令集和过程。在一个示例中，指令或软件包括由一个或更多个处理器或计算机直接执行的机器代码(诸如，由编译器产生的机器代码)。在另一示例中，指令或软件包括由一个或更多个处理器或计算机使用解释器执行的更高级代码。可基于附 图中示出的框图和流程图以及说明书中的相应描述使用任何编程语言来编写指令或软件。
计算机可读存储介质包括非暂时性计算机可读存储介质，例如，可包括诸如软盘和磁带的磁介质、光介质(包括光盘(CD)ROM和DVD ROM)、诸如软式光盘的磁光介质、设计用于存储和执行程序命令的诸如ROM、RAM的硬件装置以及闪速存储器。所述程序命令包括由计算机使用解释器可执行的语言代码以及由编译器产生的机器语言代码。上述的硬件装置可以通过用于执行本公开的各个实施例的操作的一个或更多个软件模块来实现。
本公开的模块或编程模块可以包括在省略一些部件或添加其它部件的情况下前述部件中的至少一个。所述模块、编程模块或者其它部件的操作可以顺序执行、并行执行、循环执行或试探执行。此外，一些操作可以以不同的顺序执行、可被省略或用其他操作进行扩展。
本公开的示例性实施例的计算机可读存储介质和/或前馈控制装置可以是风力发电机组的一部分，或者控制器或控制系统的一部分，也可以是风电变流器的一部分。
例如，根据本公开的示例性实施例可提供一种并网逆变器的控制器，该控制器可包括：处理器(未示出)和存储器(未示出)，其中，存储器存储有计算机程序，当所述计算机程序被处理器执行时，实现如上述示例性实施例所述的并网逆变器的前馈控制方法。
虽然已表示和描述了本公开的一些示例性实施例，但本领域技术人员应该理解，在不脱离由权利要求及其等同物限定其范围的本公开的原理和精神的情况下，可以对这些实施例进行修改，例如，可以将不同实施例的技术特征进行组合。

Claims (15)

  1. 一种并网逆变器的前馈控制方法，其特征在于，包括：
    从与所述并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号；
    基于所述谐波信号在所述第一预定频率范围内的各个频率的谐波幅值，确定与谐波幅值的最大值对应的频率；
    通过对所述电容电压进行以所述频率为中心频率的带通滤波来获得谐波电压分量；
    基于所述电容电压的基波电压分量和所述谐波电压分量获得前馈电压控制分量。
  2. 根据权利要求1所述的并网逆变器的前馈控制方法，其特征在于，从与所述并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号的步骤包括：对所述电容电压进行离散傅里叶分析以提取在所述第一预定频率范围内的谐波信号；
    基于所述谐波信号在所述第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率的步骤包括：将离散傅里叶变换后的数据转换为复数形式，计算模值，并且确定模值中的最大值以及与模值中的最大值对应的频率。
  3. 根据权利要求1所述的并网逆变器的前馈控制方法，其特征在于，所述第一预定频率范围包括预设的带通滤波器的中心频率，
    通过对所述电容电压进行以所述频率为中心频率的带通滤波来获得谐波电压分量的步骤包括：响应于所述电容电压在所述频率的电压幅值超过阈值而通过对所述电容电压进行以所述频率为中心频率的带通滤波来获得谐波电压分量。
  4. 根据权利要求1至3中的任一项所述的并网逆变器的前馈控制方法，其特征在于，基于所述电容电压的基波电压分量和所述谐波电压分量获得前馈电压控制分量的步骤包括：
    将所述基波电压分量与第一加权系数相乘以获得第一加权电压；
    将所述谐波电压分量与第二加权系数相乘以获得第二加权电压；
    将第一加权电压与第二加权电压相加以获得前馈电压控制分量。
  5. 根据权利要求4所述的并网逆变器的前馈控制方法，其特征在于，所述前馈控制方法还包括：获得所述电容电压的相角；
    其中，基于所述相角对所述电容电压进行旋转坐标转换，在旋转坐标系下对所述电容电压进行低通滤波，对滤波后的电压进行旋转坐标反变换以获得所述基波电压分量。
  6. 根据权利要求5所述的并网逆变器的前馈控制方法，其特征在于，所述前馈控制方法还包括：
    获得流过所述滤波器中的电感器的电感电流；
    通过使用所述电感电流以及所述相角的电流环获得第一输出电压；以及
    基于所述前馈电压控制分量和所述第一输出电压之和控制脉冲调制单元以控制所述并网逆变器。
  7. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有指令或程序，当所述指令或程序由处理器执行时实现根据权利要求1至6中任一项所述的前馈控制方法。
  8. 一种并网逆变器的前馈控制装置，其特征在于，包括：
    信号提取单元，被配置为从与所述并网逆变器的输出端连接的滤波器中的电容器的电容电压提取第一预定频率范围内的谐波信号；
    频率确定单元，被配置为基于所述谐波信号在所述第一预定频率范围内的各个频率的谐波幅值确定与谐波幅值的最大值对应的频率；
    带通滤波器，被配置为通过对所述电容电压进行以所述频率为中心频率的带通滤波来获得谐波电压分量；
    前馈电压控制分量获取单元，被配置为基于所述电容电压的基波电压分量和所述谐波电压分量获得前馈电压控制分量。
  9. 根据权利要求8所述的并网逆变器的前馈控制装置，其特征在于，
    所述信号提取单元被进一步配置为：对所述电容电压进行离散傅里叶变换以提取在所述第一预定频率范围内的谐波信号，
    所述频率确定单元被进一步配置为：将离散傅里叶变换后的数据转换为复数形式，计算模值，并且确定模值中的最大值以及与最大值对应的频率。
  10. 根据权利要求8所述的并网逆变器的前馈控制装置，其特征在于，所述第一预定频率范围包括预设的带通滤波器的中心频率，
    带通滤波器被进一步配置为响应于所述电容电压在所述频率的电压幅值 超过阈值而通过对所述电容电压进行以所述频率为中心频率的带通滤波来获得谐波电压分量。
  11. 根据权利要求8至10中的任一项所述的并网逆变器的前馈控制装置，其特征在于，所述前馈电压控制分量获取单元包括：
    第一电压获得单元，被配置为基于所述电容电压获得基波电压分量；
    第一比例单元，被配置为将所述基波电压分量与第一加权系数相乘以获得第一加权电压；
    第二比例单元，被配置为将谐波电压分量与第二加权系数相乘以获得第二加权电压；
    第一加法器，将第一加权电压与第二加权电压相加以获得前馈电压控制分量。
  12. 根据权利要求11所述的并网逆变器的前馈控制装置，其特征在于，所述前馈控制装置还包括：锁相环，被配置为获得所述电容电压的相角，
    所述第一电压获得单元被进一步配置为：基于所述相角对所述电容电压进行旋转坐标转换，在旋转坐标系下对所述电容电压进行低通滤波，对滤波后的电压进行旋转坐标反变换以获得所述基波电压分量。
  13. 根据权利要求12所述的并网逆变器的前馈控制装置，其特征在于，所述前馈控制装置还包括：
    电流环，被配置为通过使用所述相角以及流过所述滤波器中的电感器的电感电流获得第一输出电压；
    并网逆变器控制器，包括第二加法器和脉冲调制单元，所述第二加法器被配置为将所述前馈电压控制分量与所述第一输出电压相加以输出控制电压，所述脉冲调制单元被配置为接收所述控制电压并且向所述并网逆变器输出控制信号。
  14. 一种并网逆变器，其特征在于，包括：如权利要求8-13中任一项所述的并网逆变器的前馈控制装置。
  15. 一种风力发电机组，其特征在于，包括：如权利要求14所述的并网逆变器。
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