CN110048423A - A kind of current control method of immune Voltage Harmonic interference - Google Patents

A kind of current control method of immune Voltage Harmonic interference Download PDF

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CN110048423A
CN110048423A CN201910248416.8A CN201910248416A CN110048423A CN 110048423 A CN110048423 A CN 110048423A CN 201910248416 A CN201910248416 A CN 201910248416A CN 110048423 A CN110048423 A CN 110048423A
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phase
voltage
current
harmonic
pll
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CN110048423B (en
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韩杨
杨雄超
蒋艾町
杨孟凌
胡鹏飞
王丛岭
杨平
熊静琪
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University of Electronic Science and Technology of China
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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
    • H02J3/01—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
    • H02M7/5387—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 in a bridge configuration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a kind of current control methods of immune Voltage Harmonic interference, and in the case where Voltage Harmonic influences, grid-connected current waveform can be distorted, and then influence the tracking performance of electric current, eventually lead to the decline of the quality of grid-connected current.In order to solve this problem, the invention proposes a kind of harmonic compensation and follow-on voltage phase locking loop controlling methods.This method joined the influence that moving average filter MAF module carrys out harmonic carcellation to locking phase in traditional three-phase phase-locked loop.In addition, using voltage feed-forward control guarantees steady operation and operation of the networking electric current of inverter in the case where non-ideal power grid.Inverter side then passes through fundamental wave control loop and electric current is adjusted in harmonic wave compensating module, and wherein harmonic compensation module solves influence of the harmonic wave to current distortion, and fundamental wave control loop makes system more stable, the final reliability for guaranteeing grid-connected inverters electric current.

Description

A kind of current control method of immune Voltage Harmonic interference
Technical field
The invention belongs to the generations of electricity by new energy in electric system, micro-capacitance sensor control technology field, are related to a kind of new energy hair Electric grid-connected and power grid containing harmonic wave in the case where to the control method of grid-connected current.
Background technique
In recent years, with the continuous consumption of non-renewable energy resources, the phenomenon that energy shortages, is generally existing.Photovoltaic, wind-force etc. The development and utilization of new energy are increasingly accelerated, and distributed generation technology is increasingly taken seriously.In distributed generation system, inversion Device plays the role of interface in the conversion process of energy between renewable energy and power grid, and in distributed generation system It plays an extremely important role.However, the grid-connected current distortion of three-phase grid-connected inverter is existing since network voltage is there are harmonic wave As generally occurring.The normal work of gird-connected inverter needs accurate electric network voltage phase and frequency information simultaneously.Therefore, optimize Grid-connected current waveform and the tracking performance for improving electric current are necessary to power quality is improved.
Traditional gird-connected inverter control strategy uses proportional integration (PI) control method under dq synchronous coordinate system, to realize The tracking of the voltage-phase frequency of stable state floating.But in practical applications often by DC side fluctuation, switching device The influence of the factors such as dead time and Voltage Harmonic, so that grid-connected current waveform is distorted, current tracking electric network information Reduced capability causes serious harmonic pollution to power grid.Authorization Notice No. is that the Chinese patent of CN105763094A proposes one The inverter control method that kind is controlled based on voltage feedforward control and recombination current, this method are joined according to track with zero error It examines using the voltage prediction value of points of common connection PCC as electric voltage feed forward in voltage course and is controlled using recombination current, kept away Exempt from LCL filter and resonance occurs, improves the control precision of control algolithm.But this method is without reference to current first harmonics signal Modulation, do not refer to yet Voltage Harmonic influence in the case of network voltage locking phase problem；Authorization Notice No. is The Chinese patent of CN104037800A proposes a kind of photovoltaic combining inverter current control method.This method utilizes PID electric current Control is removed the differential component and the quadrature components that cannot achieve AC signal zero static difference sensitive to interference signal, is enhanced with this The resistivity of inverter power grid distortion and harmonic wave interference.But this method does not refer to that Voltage Harmonic is accurate electric to realizing The influence that net voltage fundamental amplitude, frequency and phase information are extracted.Since these similar algorithms are not adequately in view of electricity Influence of the net voltage harmonic to entire grid-connected system, the especially influence to grid-connected current and network voltage phase-locked loop, so, It is necessary to study the Current Control Technologies under a kind of three-phase power grid voltage harmonic environment to realize that harmonic wave is immunized in grid-connected current And can be widely applied to power Semiconductor Converting Technology, the occasions such as distributed grid-connected system.
Summary of the invention
It is an object of the invention to solve the deficiencies in the prior art, a kind of electric current of immune Voltage Harmonic interference is proposed Control method.This method technical problems to be solved be distorted by grid-connected current under the influence of Voltage Harmonic situation and The case where electric network voltage phase information can not precisely be obtained.And algorithm proposed by the present invention realizes grid-connected current wave distortion Elimination, follow-on PLL module ensure that the accuracy for obtaining network voltage information and grid-connected current and power grid phase in algorithm The synchronism of position information.To improve the robustness of entire control algolithm.
The specific technical proposal of the invention is: a kind of current control method of immune Voltage Harmonic interference, specific to wrap Include following steps:
S1, by network voltage Ea、Eb、EcInput as three-phase phase-locked loop (phase-lock loop, PLL) module is believed Number, and convert it under synchronous rotating frame and obtain voltage Ed、Eq；
S2 establishes moving average filter (moving average filter, MAF) module, then in pll modules By Ed、EqIt is separately input to carry out Harmonics elimination in moving average filter module, obtains output voltage after filteringWith
Further, three-phase power grid voltage E in the S1 and S2a、Eb、EcIt is transformed into E under synchronous rotating framed、Eq's Concrete methods of realizing are as follows:
Wherein θ is the network voltage phasor θ that phaselocked loop samplesPLL, E0For zero-sequence component.In Ed、EqIt establishes respectively below MAF module, transmission function are as follows:
Formula (2) is continuous domain expression formula, and formula (3) is discrete domain expression formula.TωIt is the length of window of MAF, wherein formula (3) is Disgrete Time Domain expression formula, wherein Tω=NTS, TSFor the sampling time, N is the sampling number in a length of window of MAF.It will S=j ω is substituted into (2), is obtained as follows:
Wherein | Gm| it is the gain factor of MAF.It can be concluded that by formula (4) as a result,
Available by formula (5), the gain of MAF module is 1 when ω=0, works as f=k/Tω(k=± 1, ± 2, ± 3 ...) gain is zero when.Particularly, shown by simulation result as length of window value TωEffect is filtered when equal to T and T/2 Fruit is more obvious, substantially filters out 5,7,11,13 subharmonic.
S3, the purpose for establishing phase advancer are to surpass phase to solve the problems, such as the phase delay as caused by MAF Front module is concatenated into behind MAF module, so effectively accelerate system responding ability and to network voltage positive-sequence component into The compensation gone in certain phase；
The transmission function of shown phase advancer are as follows:
In formula, r is decay factor, and range r ∈ [0,1), k=(1-rN)/(1-r) it is a standardized direct current sampling Gain.
S4 inputs the network voltage fundamental signal that have passed through moving average filter (MAF) and phase advancer Into ratio product integral controller (Proportional Integral Controller, PI), this period network voltage is obtained Frequency offset Δ ωi.Then by Δ ωiWith ideal power grid electric voltage frequency ω0This period network voltage frequency values are obtained after addition ωi, the electric network voltage phase value θ before this Periodic Compensation is obtained after the frequency values input to integratorPLL`；Using network voltage frequency Offset Δ ωiBy a constant gain value kφMethod, realize the phase error of compensation Park transformation, then this Periodic Compensation Preceding electric network voltage phase value θPLL` and (kφ*Δωi) the phase that is converted as Park of difference；
The phase offset as caused by MAF can be equivalent to:
When reaching stable state due to system, the phase offset of PLL is θ=θPLL`-kφΔωi, using Park transformation Rotation angle is changed to (θPLL`-kφΔωi), realize that the input signal of PI is equal to 0 when stable state.Pass through above control System can export the θ of zero error phase when reaching stable statePLL。
S5, the electric network voltage phase θ that will be traced intoPLLAs three-phase power grid voltage Ea、Eb、EcCarry out the rotation of Park transformation Angle obtains the electric voltage feed forward amount E under synchronous rotating framedq。
S6, the three-phase inverter side current data i sampleda、ib、icIt is transformed to by Clark inverse under α β reference axis Become device side electric current iαβ, electric network voltage phase θ obtained in S3PLLAs iαβThe phase for carrying out Park transformation, is converted to synchronization Electric current i under rotating coordinate systemdq, the i of inverter side samplingdqWith ideal rated value electric current idq *Subtract each other to obtain departure Δ idq, Output inverter side group wave voltage modulated signal Δ V in turn is entered into pi controller (PI)dq；
Further, Δ V is obtained in S6 stepdqImplementation are as follows:
The wherein expression formula in the domain s of proportional controller are as follows: GPI(s)=Kp+Ki/s。
S7, by electric voltage feed forward amount E obtained in S5dqWith inverter side fundamental voltage modulated signal Δ V obtained in S6dq Park inverse transformation is carried out after addition, by electric network voltage phase θ obtained in S4PLLPhase as its transformation.It is obtained after inverse transformation Voltage fundamental modulated signal Vαβ；
S8, it would be desirable to electric current idq *It carries out Park inverse transformation and is transformed into the i under α β reference axis under rotational coordinatesαβ *, so I afterwardsαβ *The electric current i sampled again with inverter side in S6αβSubtract each other, obtains the current deviation amount Δ i under α β reference axisαβ；
S9, by current deviation Δ i obtained in S8αβWith electric network voltage phase θ obtained in S4PLLAs harmonic compensator Input quantity.By current deviation amount Δ iαWith measure electric network voltage phase θPLL- 5 times of cosine value be multiplied, by current deviation Δ iβIt is multiplied with -5 times of sine value, then two product values is added to obtain Δ iq；By current deviation amount Δ iαWith measure network voltage Phasor θPLL- 5 times of sine value be multiplied, by current deviation Δ iβ5It is multiplied with -5 times of cosine value, then two product values is subtracted each other Obtain Δ id5；
The implementation method of S9 step are as follows:
S10, by Δ i obtained in S9dq5It inputs pi controller (PI), exports 5 subharmonic tune under rotating coordinate system Signal processed, while in the modulated signal input saturation limiter that this period is obtained, guarantee amplitude in a certain range.If amplitude In rated range, saturation limiter output is zero, and otherwise the amount of will exceed is adjusted to rated range through pi controller again Inside finally obtain 5 subharmonic modulated signal Δ Vd5^ and Δ Vq5^；
The 5 subharmonic modulated signal Δ V that S10 step obtainsd5^ and Δ Vq5The specific implementation of ^ are as follows:
Wherein, GPI(t)=Kpe(t)+Ki∫ e (t) dt, wherein KpFor proportionality coefficient, KiFor integration time constant.
The expression formula of saturation limiter in S9 step is as follows:
Wherein u1Value is feedback current, u2It is constant value 40, formula (11) is if be meant that u1∈(-u2,u2), then value of feedback U is zero, u1Initial value output.Otherwise, by u1And u2Difference do PI adjusting, until u1It is controlled limitation range u2Until interior.
S11, by 5 subharmonic modulated signal Δ V obtained in S10d5^ and measure network voltage phasor θPLL- 5 times remaining String value is multiplied, by harmonic modulation signal delta Vq5^ is multiplied with -5 times of sine value, then two product values are subtracted each other to obtain Δ Vα5^； By 5 subharmonic modulated signal Δ Vd5The ^ and network voltage phasor θ measuredPLL- 5 times of sine value be multiplied, by modulated signal Δ Vq5^ is multiplied with -5 times of cosine value, then two product values are mutually obtained Δ Vβ5^；
The implementation of S11 step are as follows:
Further, accomplished mode is arranged in conjunction with (9), (10), (12) formula of front are as follows:
Wherein k is 5,7,11,13 subharmonic, i.e., each harmonic modulation mode is similar.
S12, the voltage fundamental modulated signal V that single electric current closed-loop control and electric voltage feed forward modulated signal are obtainedαβAnd harmonic wave Harmonic modulation signal delta V obtained in compensatorαβThen ^, which is added, obtains three-phase voltage modulated signal by Clark inverse transformation, then Triggering letter required for inverter H bridge IGBT is constructed after pulse width-modulated (Pulse width modulation, PWM) Number.
Compared with prior art, the beneficial effects of the present invention are:
1. the present invention adjusts the fundamental wave harmony wave of grid-connected current in traditional grid-connected inverters system respectively System, fundamental modulation ensure that the stabilization of grid-connected current, harmonic modulation then eliminate influence of the Voltage Harmonic to grid-connected current；
2. follow-on voltage phaselocked loop includes the MAF module for eliminating the influence of Voltage Harmonic, furthermore have also been devised Phase compensator compensates phase, realizes accurate extraction network voltage information, enhances the robustness of phaselocked loop, from And improve the precision of grid-connected system current control.
Detailed description of the invention
The whole functional block diagram of Fig. 1 gird-connected inverter grid-connected current control system；
Fig. 2 network voltage fundamental frequency, phase extraction functional block diagram；
The topological structure functional block diagram of Fig. 3 particular harmonic cancellation module；
Fig. 4 moving average filter (MAF) is as length of window value TωFilter effect Bode diagram when equal to T and T/2；
Fig. 5 MAF has cascaded compensation effect Bode diagram of the phase advancer to phase of three difference r values；
Three-phase grid electric current (the I before Harmonics elimination module and voltage on line side feedforward is added in Fig. 6A,IB,IC) simulation waveform；
Three-phase grid electric current (the I before Harmonics elimination module is added in Fig. 7A,IB,IC) simulation waveform；
Three-phase grid electric current (the I before voltage on line side feedforward amount is added in Fig. 8A,IB,IC) simulation waveform；
Three-phase grid electric current (the I after voltage on line side feedforward amount and harmonic wave cancellation module is added in Fig. 9A,IB,IC) simulation waveform；
The simulation waveform comparison of three-phase grid active power and reactive power before and after Figure 10 addition voltage on line side feedforward amount Figure.
Specific embodiment
Elaborate with reference to the accompanying drawing to the embodiment of the present invention: the present embodiment before being with technical solution of the present invention It puts and is implemented, the detailed implementation method and specific operation process are given, but protection scope of the present invention is not limited to down The embodiment stated.
It is as shown in Figure 1 the whole functional block diagram of three-phase grid-connected inverter grid-connected current control system.It is humorous in network voltage Grid-connected current waveform can be distorted in the case where wave action, and then influence the tracking performance of electric current, eventually lead to grid-connected electricity The decline of the quality of stream.So whole system mainly includes the modified phase-locked loop module of net side, inverter as can be seen from Figure 1 The fundamental wave control loop and particular harmonic adjustment module of side electric current.Wherein modified phase-locked loop module is to the accurate fast of network voltage The phase extraction of speed；Current first harmonics control loop has modified the deviation as caused by harmonic voltage；Particular harmonic adjustment module then disappears In addition to the harmonic content in grid-connected current, so that grid-connected current quality meets Grid-connection standards.
Implemented in accordance with the following steps according to the functional block diagram of Fig. 1:
S1, by network voltage Ea、Eb、EcInput as three-phase phase-locked loop (phase-lock loop, PLL) module is believed Number, and convert it under synchronous rotating frame and obtain voltage Ed、Eq；
S2 establishes moving average filter (moving average filter, MAF) module, then in pll modules By Ed、EqIt is separately input to carry out Harmonics elimination in moving average filter module, obtains output voltage after filteringWith
Further, if Fig. 2 is network voltage fundamental frequency, phase extraction functional block diagram, the i.e. controller chassis of PLL module Figure.Three-phase power grid voltage E in the S1 and S2a、Eb、EcIt is transformed into E under synchronous rotating framed、EqConcrete methods of realizing are as follows:
Wherein θ is the network voltage phasor θ that phaselocked loop samplesPLL, E0For zero-sequence component.In Ed、EqIt establishes respectively below MAF module, transmission function are as follows:
Formula (2) is continuous domain expression formula, and formula (3) is discrete domain expression formula.TωIt is the length of window of MAF, wherein formula (3) is Disgrete Time Domain expression formula, wherein Tω=NTS, TSFor the sampling time, N is the sampling number in a length of window of MAF.It will S=j ω is substituted into (2), is obtained as follows:
Wherein | Gm| it is the gain factor of MAF.It can be concluded that by formula (4) as a result,
Available by formula (5), the gain of MAF module is 1 when ω=0, works as f=k/Tω(k=± 1, ± 2, ± 3 ...) gain is zero when.Particularly, simulation result shows as length of window value T as shown in Figure 4ωWhen equal to T and T/2 Filter effect is more obvious, substantially filters out 5,7,11,13 subharmonic.
S3, the purpose for establishing phase advancer are to surpass phase to solve the problems, such as the phase delay as caused by MAF Front module is concatenated into behind MAF module, so effectively accelerate system responding ability and to network voltage positive-sequence component into The compensation gone in certain phase；
The transmission function of shown phase advancer are as follows:
In formula, r is decay factor, and range r ∈ [0,1), k=(1-rN)/(1-r), it is that a standardized direct current is adopted Sample gain.
S4 inputs the network voltage fundamental signal that have passed through moving average filter (MAF) and phase advancer Into ratio product integral controller (Proportional Integral Controller, PI), this period network voltage is obtained Frequency offset Δ ωi.Then by Δ ωiWith ideal power grid electric voltage frequency ω0This period network voltage frequency values are obtained after addition ωi, the electric network voltage phase value θ before this Periodic Compensation is obtained after the frequency values input to integratorPLL`；Using network voltage frequency Offset Δ ωiBy a constant gain value kφMethod, realize the phase error of compensation Park transformation, then this Periodic Compensation Preceding electric network voltage phase value θPLL` and (kφ*Δωi) the phase that is converted as Park of difference；
The phase offset as caused by MAF can be equivalent to:
When reaching stable state due to system, the phase offset of PLL is θ=θPLL`-kφΔωi, using Park transformation Rotation angle is changed to (θPLL`-kφΔωi), realize that the input signal of PI is equal to 0 when stable state.Pass through above control System can export the θ of zero error phase when reaching stable statePLL。
The jump amplitude of S5, active power are very big, will lead to that energy impact is excessive to be caused to damage to grid-connected system, so Introduce electric voltage feed forward.In the whole functional block diagram of gird-connected inverter grid-connected current control system as shown in Figure 1, the electricity that will trace into Net voltage-phase θPLLAs three-phase power grid voltage Ea、Eb、EcThe rotation angle for carrying out Park transformation, obtains synchronous rotating frame Under electric voltage feed forward amount Edq。
S6, the three-phase inverter side current data i sampleda、ib、icIt is transformed to by Clark inverse under α β reference axis Become device side electric current iαβ, electric network voltage phase θ obtained in S3PLLAs iαβThe phase for carrying out Park transformation, is converted to synchronization Electric current i under rotating coordinate systemdq, the i of inverter side samplingdqWith ideal rated value electric current idq *Subtract each other to obtain departure Δ idq, Output inverter side group wave voltage modulated signal Δ V in turn is entered into pi controller (PI)dq；
Further, Δ V is obtained in S6 stepdqImplementation are as follows:
The wherein expression formula in the domain s of proportional controller are as follows: GPI(s)=Kp+Ki/ s, wherein KpFor proportionality coefficient, KiFor integral Time constant,WithIt is quantitative for the current capacity under dq coordinate system.ia、ibAnd icFor inverter end three-phase current.
S7, by electric voltage feed forward amount E obtained in S5dqWith inverter side fundamental voltage modulated signal Δ V obtained in S6dq Park inverse transformation is carried out after addition, by electric network voltage phase θ obtained in S4PLLPhase as its transformation.It is obtained after inverse transformation Voltage fundamental modulated signal Vαβ；
S8, it would be desirable to electric current idq *It carries out Park inverse transformation and is transformed into the i under α β reference axis under rotational coordinatesαβ *, so I afterwardsαβ *The electric current i sampled again with inverter side in S6αβSubtract each other, obtains the current deviation amount Δ i under α β reference axisαβ；
S9, by current deviation Δ i obtained in S8αβWith electric network voltage phase θ obtained in S4PLLAs harmonic compensator Input quantity.By current deviation amount Δ iαWith measure electric network voltage phase θPLL- 5 times of cosine value be multiplied, by current deviation Δ iβIt is multiplied with -5 times of sine value, then two product values is added to obtain Δ iq5；By current deviation amount Δ iαIt is electric with power grid is measured Press phasor θPLL- 5 times of sine value be multiplied, by current deviation Δ iβ5It is multiplied with -5 times of cosine value, then by two product value phases Subtract to obtain Δ id5；
It is 5,7,11,13 subharmonic compensation control block diagram, the implementation method of S9 step as shown in Figure 3 are as follows:
S10, by Δ i obtained in S9dq5It inputs pi controller (PI), exports 5 subharmonic tune under rotating coordinate system Signal processed, while in the modulated signal input saturation limiter that this period is obtained, guarantee amplitude in a certain range.If amplitude In rated range, saturation limiter output is zero, and otherwise the amount of will exceed is adjusted to rated range through pi controller again Inside finally obtain 5 subharmonic modulated signal Δ Vd5^ and Δ Vq5^；
The 5 subharmonic modulated signal Δ V that S10 step obtainsd5^ and Δ Vq5The specific implementation of ^ are as follows:
Wherein, GPI(t)=Kpe(t)+Ki∫ e (t) dt, wherein KpFor proportionality coefficient, KiFor integration time constant.
Fcn module is to limit saturator in control block diagram as shown in Figure 3, the expression of the saturation limiter in S9 step Formula is as follows:
Wherein u1Value is feedback current, u2It is constant value 40, formula (11) is if be meant that u1∈(-u2,u2), then value of feedback U is zero, u1Initial value output.Otherwise, by u1And u2Difference do PI adjusting, until u1It is controlled limitation range u2Until interior.
S11, by 5 subharmonic modulated signal Δ V obtained in S10d5^ and measure network voltage phasor θPLL- 5 times remaining String value is multiplied, by harmonic modulation signal delta Vq5^ is multiplied with -5 times of sine value, then two product values are subtracted each other to obtain Δ Vα5^； By 5 subharmonic modulated signal Δ Vd5The ^ and network voltage phasor θ measuredPLL- 5 times of sine value be multiplied, by modulated signal Δ Vq5^ is multiplied with -5 times of cosine value, then two product values are mutually obtained Δ Vβ5^；
The implementation of S11 step are as follows:
Further, accomplished mode is arranged in conjunction with (9), (10), (12) formula of front are as follows:
Wherein k is 5,7,11,13 subharmonic, i.e., each harmonic modulation mode is similar.
S12, the voltage fundamental modulated signal V that single electric current closed-loop control and electric voltage feed forward modulated signal are obtainedαβAnd harmonic wave Harmonic modulation signal delta V obtained in compensatorαβThen ^, which is added, obtains three-phase voltage modulated signal by Clark inverse transformation, then Triggering letter required for inverter H bridge IGBT is constructed after pulse width-modulated (Pulse width modulation, PWM) Number.
It can accurately be obtained in the case where containing Voltage Harmonic to verify modified phaselocked loop proposed by the invention Electric network voltage phase and frequency information are obtained, Fig. 4~Fig. 5 is the MAF module of PLL module and the emulation effect of phase lead compensation module Fruit figure.In order to verify the shadow that particular harmonic compensating module feedovers to three-phase grid electric current to the compensation effect and voltage on line side of harmonic wave It rings, Fig. 6 is to keep that particular harmonic compensating module and the voltage on line side feedforward grid-connected electricity of three-phase are added in the constant situation of other conditions The waveform diagram of stream.Fig. 7 is the wave for keeping being added particular harmonic compensating module three-phase grid-connected current in the constant situation of other conditions Shape figure.Fig. 8 is the waveform diagram for keeping being added the three-phase grid electric current before voltage on line side feedforward in the constant situation of other conditions.Fig. 9 For the three-phase grid current waveform figure after particular harmonic compensating module and voltage on line side feedforward is added.Before verifying voltage on line side The influence to three-phase grid active power and reactive power is presented, Figure 10 is that voltage on line side is added in the situation for keeping other conditions constant Three-phase grid active power and reactive power comparison of wave shape before and after feedforward amount.
After introduction based on Fig. 4~Figure 10 service condition, separately below to the dynamic effect of Fig. 4~Figure 10 and comparison waveform It is described in detail.
Fig. 4 gives the Bode diagram that MAF module voltage phase-locked loop systems are added, it can be observed that phase margin is 43.3 °, Show that follow-on phase-locked loop systems are stablized, while mains by harmonics ingredient is effectively filtered out, but can obviously be observed and be filtered out There is apparent phase delay while harmonic wave.Fig. 5 gives the Bode diagram of MAF module cascade phase lead compensation module, curve 1 It is the frequency response situation of no cascade phase lead compensation module, other curves are that MAF module has cascaded phase lead compensation Frequency response situation after module.Wherein the r value of curve 2 is taken as 0.95, and the r value of curve 3 is taken as 0.97, and the r value of curve 4 is taken as 0.99.It can be observed that phase lead compensation module effectively offsets the delay in the phase as caused by MAF module while also disappearing In addition to harmonic wave, the compensation effect of curve 4 is optimal.Fig. 6 gives whole system and lacks harmonic modulation signal and voltage on line side feedforward Three-phase grid electric current (the I of signala, Ib, Ic) waveform diagram output situation, in the section t=0~0.05s, a, b, c three-phase current Amplitude fluctuations it is very big.Simultaneously because the influence of Voltage Harmonic, the current distortion of three-phase is very serious, and with the time This distortion is elapsed to always exist.Fig. 7 gives whole system three-phase grid electric current in the case where lacking harmonic modulation signal (Ia, Ib, Ic) output situation, it can be seen that under the influence of Voltage Harmonic, obvious distortion is had occurred in three-phase current.Figure 8 give the three-phase grid electric current (I in the case that whole system lacks voltage on line side feedforwarda, Ib, Ic) waveform diagram output feelings Condition, it can be seen that in the case where lacking voltage on line side feedforward, within the period of 0~0.05s, three-phase current amplitude jump And it is very serious, wherein c phase hopping amplitude is the largest, and in t=0~0.04s period, there is also abnormal for three-phase current waveform Become, and the case where distortion degree ratio Fig. 7, is big, but due to harmonic modulation signal under the action of, the three-phase current after 0.4s The distortion of waveform gradually eliminates, and the current waveform of a, b, c three-phase is smoothened symmetrical.Fig. 9 gives in harmonic modulation signal With the three-phase grid current waveform output waveform of whole system under voltage on line side feedforward action.It is electric within t=0~0.2s period Stream wave distortion substantially eliminates, while also eliminating the case where current amplitude jumps, and the current waveform of a, b, c three-phase is smoothened Symmetrically.
Figure 10 give whole system lack voltage on line side feedforward in the case where three-phase grid active power and idle function Rate comparison of wave shape.A figure amplitude jump range of active power and reactive power within t=0~0.03s period is very big, and B schemes then It is the waveform of the active power and reactive power after voltage on line side feedforward is added, it is easily observed that active power as time goes by It is gradually stable with reactive power, and fluctuate very little.
It is proposed by the present invention right that three-phase current waveform and power waveform comparison under above-mentioned various different control conditions show The fundamental wave of grid-connected current, humorous wave modulation eliminate influence of the mains by harmonics to current waveform；Electric voltage feed forward makes whole system It is more reliable and stable；Follow-on voltage phaselocked loop then improves the control precision of whole system.This immune network voltage The current control mode of harmonic wave interference can be widely applied in distributed generation system.
Those of ordinary skill in the art will understand that the embodiments described herein, which is to help reader, understands this hair Bright principle, it should be understood that protection scope of the present invention is not limited to such special statement and case study on implementation.This field Those of ordinary skill disclosed the technical disclosures can make according to the present invention and various not depart from the other of essence of the invention Various specific variations and combinations, these variations and combinations are still within the scope of the present invention.

Claims (3)

1. a kind of current control method of immune Voltage Harmonic interference, which is characterized in that comprise the following specific steps that:
S1, by network voltage Ea、Eb、EcSynchronous rotation is transformed into as the input signal of three-phase phase-locked loop module, and by network voltage Turn under coordinate system, i.e. Ed、Eq；
S2 establishes moving average filter module in pll modules, by network voltage Ed、EqIt is respectively delivered to moving average filter Harmonics elimination is carried out in device MAF, obtains output voltage after filteringWith
S3, in order to solve the problems, such as that the phase delay as caused by MAF establishes phase advancer, by Phase lead block string It is connected to behind MAF module, and then effectively accelerates system responding ability, furthermore Phase lead block is to network voltage positive-sequence component Also play certain effect of phase compensation；
The network voltage fundamental signal that have passed through moving average filter and phase advancer is input to ratio product product by S4 In sub-controller PI, this period network voltage frequency offset Δ ω is obtainedi；Then by Δ ωiWith ideal power grid electric voltage frequency ω0This period network voltage frequency values ω is obtained after additioni, which is transported to after integrator obtain this Periodic Compensation before Electric network voltage phase value θPLL`；In addition, using network voltage frequency offset Δ ωiBy a constant gain value kφ, realize The phase error of Park transformation is compensated, then the electric network voltage phase value θ before this Periodic CompensationPLL` and kφ*ΔωiPoor conduct The phase of Park transformation；
S5, the electric network voltage phase θ that will be traced intoPLLAs three-phase power grid voltage Ea、Eb、EcCarry out the rotation angle of Park transformation Degree, obtains the electric voltage feed forward amount E under synchronous rotating framedq；
S6, the three-phase inverter side current data i sampleda、ib、icThe inverter under α β reference axis is transformed to by Clark Side electric current iαβ, electric network voltage phase θ obtained in S3PLLAs iαβThe phase for carrying out Park transformation, is converted to synchronous rotary Electric current i under coordinate systemdq, the i of inverter side samplingdqWith ideal rated value electric current idq *Subtract each other to obtain departure Δ idq, by its Output inverter side group wave voltage modulated signal Δ V in turn is input in pi controller PIdq；
S7, by electric voltage feed forward amount E obtained in S5dqWith inverter side fundamental voltage modulated signal Δ V obtained in S6dqAfter addition Park inverse transformation is carried out, by electric network voltage phase θ obtained in S4PLLAs the phase of its transformation, voltage base is obtained after inverse transformation Wave modulated signal Vαβ；
S8, it would be desirable to electric current idq *It carries out Park inverse transformation and is transformed into the i under α β reference axis under rotational coordinatesαβ *, then iαβ * The electric current i sampled again with inverter side in S6αβSubtract each other, obtains the current deviation amount Δ i under α β reference axisαβ；
S9, by current deviation Δ i obtained in S8αβWith electric network voltage phase θ obtained in S4PLLAs the defeated of harmonic compensator Enter amount；By current deviation amount Δ iαWith measure electric network voltage phase θPLL- 5 times of cosine value be multiplied, by current deviation Δ iβWith- 5 times of sine value is multiplied, then two product values are added to obtain Δ iq；By current deviation amount Δ iαWith measure network voltage phasor θPLL- 5 times of sine value be multiplied, by current deviation Δ iβ5It is multiplied with -5 times of cosine value, then two product values is subtracted each other to obtain Δid5；
S10, by Δ i obtained in S9dq5Pi controller PI is inputted, 5 subharmonic modulation letter under rotating coordinate system is exported Number, while in the modulated signal input saturation limiter that this period is obtained, guarantee amplitude in a certain range；If amplitude is in volume Determine in range, saturation limiter output is zero, and otherwise the amount of will exceed is adjusted in rated range most through pi controller again 5 subharmonic modulated signal Δ V are obtained eventuallyd5^ and Δ Vq5^；
S11, by 5 subharmonic modulated signal Δ V obtained in S10d5^ and measure network voltage phasor θPLL- 5 times of cosine value It is multiplied, by harmonic modulation signal delta Vq5^ is multiplied with -5 times of sine value, then two product values are subtracted each other to obtain Δ Vα5^；By 5 times Harmonic modulation signal delta Vd5The ^ and network voltage phasor θ measuredPLL- 5 times of sine value be multiplied, by modulated signal Δ Vq5^ It is multiplied with -5 times of cosine value, then two product values is mutually obtained into Δ Vβ5^；
S12, the voltage fundamental modulated signal V that single electric current closed-loop control and electric voltage feed forward modulated signal are obtainedαβAnd harmonic compensation Harmonic modulation signal delta V obtained in deviceαβThen ^, which is added, obtains three-phase voltage modulated signal, then passages through which vital energy circulates by Clark inverse transformation Trigger signal required for inverter H bridge IGBT is constructed after rushing width modulated PWM.
2. a kind of current control method of immune Voltage Harmonic interference according to claim 1, which is characterized in that step S1~S4 is the process of accurate tracking electric network voltage phase, advanced using moving average filter and phase in this control process Compensator eliminates influence of the mains by harmonics to it, and detailed process is as follows:
Three-phase power grid voltage E in the S1 and S2a、Eb、EcIt is transformed into E under synchronous rotating framed、EqConcrete methods of realizing Are as follows:
Wherein θ is the network voltage phasor θ that phaselocked loop samplesPLL, E0For zero-sequence component；In Ed、EqEstablish MAF mould respectively below Block, transmission function are as follows:
Formula (2) is continuous domain expression formula, and formula (3) is discrete domain expression formula；TωIt is the length of window of MAF, wherein formula (3) is discrete Time-domain expression formula, wherein Tω=NTS, TSFor the sampling time, N is the sampling number in a length of window of MAF；By s=j ω is substituted into (2), is obtained as follows:
Wherein | Gm| it is the gain factor of MAF, can be concluded that by formula (4)
Available by formula (5), the gain of MAF module is 1 when ω=0, works as f=k/Tω(k=± 1, ± 2, ± 3 ...) When gain be zero；Particularly, shown by simulation result as length of window value TωWhen equal to T and T/2 filter effect compared with To be obvious, 5,7,11,13 subharmonic are filtered out substantially；
The transmission function of phase advancer in the S3 are as follows:
In formula, r is decay factor, and range r ∈ [0,1), k=(1-rN)/(1-r), it is that a standardized direct current sampling increases Benefit；
The phase offset as caused by MAF can be equivalent in the S4:
K in formulaφFor constant gain value, Δ ωiFor the offset between network voltage frequency and rated value；Since system reaches When stable state, the phase offset of PLL is θ=θPLL`-kφΔωi, θ is changed to using the rotation angle that Park is convertedPLL`-kφ Δωi, realize that the input signal of PI is equal to 0 when stable state, by above control, can be exported when reaching stable state The θ of zero error phasePLL；
Further, the jump amplitude according to the active power of simulation data system output is excessive, and energy impact is crossed conference and led Cause causes to damage to grid-connected system, so step S5 is using the method for introducing electric voltage feed forward come the active power of systems stabilisation；Step Rapid S6~S7 is to obtain fundamental voltage modulated signal and voltage fundamental modulated signal VαβProcess, wherein step S6 fundamental voltage tune Signal delta V processeddqSpecific implementation are as follows:
The wherein expression formula in the domain s of proportional controller are as follows: GPI(s)=Kp+Ki/ s, wherein KpFor proportionality coefficient, KiFor the time of integration Constant,WithQuantitative, the i for the current capacity under dq coordinate systema、ibAnd icFor inverter end three-phase current.
3. a kind of current control method of immune Voltage Harmonic interference according to claim 1, which is characterized in that step S8~S11 is to obtain 5,7,11,13 subharmonic modulated signal Δ VαβThe implementation of ^, the realization side of each harmonic modulated signal Formula be it is identical, below by taking 5 subharmonic modulated signals as an example:
S9 step obtains Δ iqWith Δ id5Concrete methods of realizing are as follows:
The 5 subharmonic modulated signal Δ V that S10 step obtainsd5^ and Δ Vq5The specific implementation of ^ are as follows:
Wherein, GPI(t)=Kpe(t)+Ki∫ e (t) dt, wherein KpFor proportionality coefficient, KiIt is normal for the time of integration；
The expression formula of saturation limiter in S9 step is as follows:
Wherein u1Value is feedback current, u2It is constant value 40, formula (11) is if be meant that u1∈(-u2,u2), then value of feedback u is Zero, u1Initial value output；Otherwise, by u1And u2Difference do PI adjusting, until u1It is controlled limitation range u2Until interior；
S11 step obtains Δ Vα5^ and Δ Vβ5The specific implementation of ^ are as follows:
Further, it arranges to obtain harmonic modulation signal implementation in conjunction with (9) of front, (10), (12) formula are as follows:
Wherein k is 5,7,11,13 subharmonic, i.e., each harmonic modulation mode is similar；
Finally, the voltage fundamental modulated signal V that single electric current closed-loop control and electric voltage feed forward modulated signal are obtainedαβAnd harmonic compensation Harmonic modulation signal delta V obtained in deviceαβThen ^, which is added, obtains three-phase voltage modulated signal, then passages through which vital energy circulates by Clark inverse transformation Trigger signal required for inverter H bridge IGBT is constructed after rushing width modulated PWM.
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CN111541366A (en) * 2020-05-07 2020-08-14 上海交通大学 Grid-connected inverter and dead zone phase shift compensation method thereof
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CN111541365B (en) * 2020-05-07 2021-06-29 上海交通大学 Unit modulation degree control method of variable-frequency speed-regulating inverter and application thereof
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