CN110768280A - Grid-connected inverter current control method - Google Patents

Grid-connected inverter current control method Download PDF

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CN110768280A
CN110768280A CN201910887398.8A CN201910887398A CN110768280A CN 110768280 A CN110768280 A CN 110768280A CN 201910887398 A CN201910887398 A CN 201910887398A CN 110768280 A CN110768280 A CN 110768280A
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grid
current
control
controller
inverter
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谭翠兰
周利华
熊琰
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Jianghan University
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Jianghan University
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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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L55/00—Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
    • 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
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Abstract

The invention relates to a grid-connected inverter current control method, which comprises the following steps: the three-phase four-bridge arm inverter circuit is decoupled into three independent single-phase loops for control, the inductive currents on the inverter side and the grid-connected side are respectively detected by two current sensors, the weighted average of the two inductive currents is used as a feedback signal, the three-order LCL inverter can be simplified to be one order, and the influence of inductance parameter change on system stability is reduced by introducing inductance coefficients. Meanwhile, the fractional order repetitive controller inhibits periodic disturbance and harmonic waves and realizes accurate tracking of the given current. The grid-connected inverter current control method is simple, efficient, easy to implement and strong in anti-interference capability when applied to V2G grid-connected inverter current control.

Description

Grid-connected inverter current control method
Technical Field
The invention relates to the technical field of power transformation and control, in particular to a grid-connected inverter current control method.
Background
Large-scale application of Electric Vehicles (EVs) and renewable energy is an effective way to deal with the problems of gradual depletion of primary energy, global warming, environmental pollution, and the like. However, electric vehicles and renewable energy sources have intermittency, randomness and uncertainty, and their massive access inevitably has new influence on the safety, quality and economic operation of power transmission and distribution systems, and brings important challenges to the traditional power grid architecture and technology, the reliability and stability of the power system. Studies have shown that over 90% of electric vehicles have an average daily driving time of about 1 hour, and that they remain parked for most of the time, which in fact represents an idle resource. If the electric vehicles in a stopped state can be connected to the power Grid, when the number of the electric vehicles is large enough, the electric vehicles can absorb energy from the power Grid in the low-ebb of electricity consumption and can feed the energy back to the power Grid in the high-ebb of electricity consumption so as to reduce the peak-valley difference of daily electricity consumption load, which is actually the concept of Vehicle-to-Grid (V2G). Through technologies such as V2G, the problems of insufficient operation adequacy of a power grid, low efficiency, seriously limited renewable energy source accepting capability, inflexible charging and discharging of an electric automobile, uneconomic use and the like can be relieved to different degrees, and for electric automobile users, benefits can be obtained by means of V2G so as to offset part of the cost for purchasing the electric automobile.
The inverter is used as an interface unit for energy exchange between an electric automobile and a power grid, the control algorithm of the inverter determines the quality and efficiency of electric energy injected into the power grid, the traditional V2G grid-connected inverter current control method enables the quality of current injected into the power grid to be easily affected by power grid frequency fluctuation, and the defects of low steady-state precision and slow dynamic response exist.
Disclosure of Invention
The invention provides a grid-connected inverter current control method, solves the technical problems of low steady-state precision and slow dynamic response of the traditional V2G grid-connected inverter current control method, provides a simple high-performance grid-connected inverter current control method, improves the dynamic performance and steady-state performance of a system and the capability of inhibiting periodic interference, and can improve the quality of electric energy injected into a power grid in V2G application.
The grid-connected inverter current control method is realized by an electric energy storage component, an LCL type three-phase four-leg power conversion inverter circuit and a controller, wherein the controller controls the on-off of an Insulated Gate Bipolar Transistor (IGBT) in the LCL type three-phase four-leg power conversion inverter circuit, inverts the direct current of the electric energy storage component into alternating current and is connected to a power grid through a filter circuit and a grid-connected relay; the controller includes: a dead-beat predictive controller and a fractional order repetitive controller based on the weighted average inductor current; the grid-connected inverter current control method comprises the following steps:
decoupling the three-phase four-bridge-arm power conversion inverter circuit into three independent single-phase loops for control, introducing weighted current dead-beat control, and converting a three-order object into a first-order model;
introducing a predicted inductance coefficient as a ratio of a predicted inductance value and an actual inverter side inductance value in a control algorithm;
embedding the fractional order repetitive controller into a control algorithm of the weighted current dead-beat control to form dead-beat frequency self-adaptive control;
the controller collects the voltage phase of the power grid in real time, calculates the reference value of grid-connected current at the next moment according to the voltage phase, sends an error signal into the controller, obtains and normalizes an output voltage control value at an inversion side, and controls the on and off of the insulated gate bipolar transistor through pulse width modulation.
Preferably, the introducing of weighted current dead-beat control includes selecting a weighting coefficient as a ratio of an inverter-side inductance to a sum of the two inductances, that is, the weighting coefficient α ═ L1/(L1+L2) The feedback current is a weighted average value of the inverter side inductive current and the grid-connected side inductive current, i is α i1+(1-α)i2The third order system is reduced to the first order by introducing a weighted average inductor current.
Preferably, the introduced predicted inductance K is a number smaller than 1, and the value range of the predicted inductance K is determined by adopting a root trajectory for the delayed beat number of the controlled object.
Preferably, the fractional order repetitive controller is connected in parallel with the deadbeat controller;
the fractional order repetitive controller GrcThe design of (z) specifically comprises:
approximating fractional order delay by Lagrange interpolation, noting the sampling frequency as fsGrid frequency of f0When f is0When the change is in a small range, the notation N ═ fs/f0＝ND+M，NDIs an integer part, M is a fractional part,
Figure BDA0002207732460000031
approximation of fractional order delay using lagrange interpolationDelay each term coefficient of
Introducing a repetitive control coefficient K into fractional order repetitive controlrcIntroducing a low-pass filter Q (z) a without phase offset0z+a1+a0Z, wherein 2a0+a1＝1；
The linear phase lead compensation module is introduced into the fractional order repetitive control and is Gf(z)＝zpAdvance compensation of beat number
Figure BDA0002207732460000034
Preferably, the electric energy storage component is an electric vehicle or a battery pack.
The grid-connected inverter current control method provided by the application at least has the following technical effects or advantages:
according to the simple high-performance grid-connected inverter current control method, a weighted average current method is adopted, a three-order system is reduced to the first order, control is simplified, and dynamic response of the system is improved through dead-beat current control based on weighted current; a fractional order repetitive controller is embedded in the current control of the grid-connected inverter, so that the frequency fluctuation of a power grid can be adapted, and the tracking precision is improved; the three-phase four-bridge-arm grid-connected inverter can be directly decoupled into three independent single-phase loops, and the design is simplified. The invention improves the dynamic performance and the steady-state performance of the system and the capability of inhibiting periodic interference, and can improve the quality of the electric energy injected into a power grid in the application of V2G.
Drawings
FIG. 1 is a three-phase four-leg inverter topology and control structure for charging and discharging the function of the pile according to the present invention;
FIG. 2 is a block diagram of a fractional order repetitive controller;
FIG. 3 is a single phase block diagram based on weighted current;
FIG. 4 is a block diagram of a controlled system with a delay;
FIG. 5 is a plot of traces for different time-lapse beats;
FIG. 6 is an amplitude-frequency response of a conventional integer-order repetitive controller when the grid frequency fluctuates;
FIG. 7 is an amplitude-frequency response at the 7 th harmonic for conventional integer and fractional order repetition control;
FIG. 8 is a diagram of a system baud at different compensated beats;
FIG. 9 is a simulation diagram of the steady-state waveform of the actual grid-connected current controlled by the integer order weight of dead-beat control;
fig. 10 is a simulation diagram of an actual grid-connected current steady-state waveform of fractional order repetitive control.
The meaning of the reference symbols in the drawings is as follows:
Q1-Q8 are IGBT high-power switching tubes, L1An inverter side inductor; l is2The inductance is the grid-connected side inductance; cfThe filter capacitor is R, and the filter capacitor is a series resistor. Theta is the current grid voltage phase detected by a Phase Locked Loop (PLL) in real time at each sampling period, i*α is a weighted current coefficient, i is the actual three-phase grid-connected current, v is the effective value of the grid-connected given current which is calculated according to the phase angle theta and is in the same phase with the grid voltagega,vgb,vgcThe three-phase grid voltage is A, B and C.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The invention provides a deadbeat fractional order repetitive control method of a V2G grid-connected inverter, which comprises a new energy electric vehicle or a storage battery pack, a power conversion circuit, a filter circuit, a grid-connected relay and a controller. The controller includes: design of weighted current based dead-beat predictive controller and fractional order repetitive controller. The controller inverts direct current output by the new energy electric vehicle into alternating current by controlling the on and off of the IGBT in the power conversion circuit, and the alternating current is merged into a power grid through the filter circuit and the grid-connected relay. The method specifically comprises the following steps: decoupling a three-phase four-bridge arm inverter circuit into three independent single-phase loops for control; the weighted average current of two inductors is taken for an LCL type third-order filter, and a third-order system is simplified into a first-order system; the stability of the system is improved by introducing a prediction inductance coefficient into the dead beat controller; embedding a fractional order repetitive controller in a dead beat control algorithm to cope with power grid frequency fluctuation, wherein the design of the fractional order repetitive controller comprises the following steps: approximating fractional order delay by adopting a Lagrange interpolation method, and determining a repetitive controller structure and an internal model low-pass filter Q (z); introducing a linear phase lead compensation module zPAnd the phase angle is compensated to ensure that the grid-connected current and the voltage have no phase difference. Under the combined action of weighted current dead-beat control and fractional order repetitive controller, the controller obtains the control value of the output voltage of the inverter side and normalizes the control value, and the on-off of the IGBT in the power conversion circuit is controlled through PWM modulation. Parameters of the experimental platform of the three-phase four-leg inverter for charging and discharging the pile function are shown in attached table 1.
TABLE 1
Parameter(s) Rated value Unit of
DC voltage Udc 700 V
Inverter side filter inductor L f 3 mH
Inverter-side equivalent resistor R1 0.5 Ω
Filter capacitor C f 5 uF
Damping resistor R 24 Ω
Power grid side filter inductor L 2 1 mH
Equivalent resistance R on power grid side2 0.5 Ω
Effective value u of grid voltageg 220 V
Frequency f of the grid 50 Hz
Sampling frequency f s 20 kHz
Rated output current I* 15 A
Rated output power P 10 kW
In the design example of the invention, the dead-beat repetitive controller design method of the grid-connected inverter adopts dead-beat control based on the weighted current to reduce the third order to one order, thereby simplifying the design of a control system. Determining a dead beat control structure chart with time delay, discretizing a controlled object by adopting a zero-order retainer, determining the range of a predicted inductance value by utilizing a root track, and selecting a constant with the predicted inductance coefficient smaller than 1.
For fractional order repeat controller Grc(z) design, adopting Lagrange interpolation to approach fractional delay, introducing repetition control coefficient KrcIntroducing a low-pass filter Q (z) a without phase offset0z+a1+a0Z, wherein 2a0+a11. The introduced linear phase lead compensation module is Gf(z)＝zpAdvance compensation of beat number
Figure BDA0002207732460000063
The structure block diagram of the repetitive controller is shown in figure 2.
And for the selection of the compensation beat number of the repetitive controller, selecting a leading compensation beat number p according to a filter model of a controlled system, wherein the selected compensation beat number is required to enable the bandwidth of the system to be maximum.
Connecting the fractional order repetitive controller with the dead-beat controller based on the weighted current in the figure 4 in parallel, and if the time delay is not considered, the closed loop transfer function of the current loop is:
Figure BDA0002207732460000061
wherein G iso(z)＝Gp(z)·[1+G1(z)Gp(z]-1If the following two conditions are met, the system is stable:
1) the original system being stable, i.e. GOAre all within the unit circle,
2) the characteristic roots of the closed-loop system are all within the unit circle, i.e. 1- [1-K ] the system is stablerczPGp(z)]Q(z)z-NThe root being 0 within the unit circle, i.e. for all
Figure BDA0002207732460000062
The following holds: a (z) ═ 1-krczpGo(z)]Q(z)|＜1。
Aiming at the defects of low steady-state precision and slow dynamic response of the traditional V2G grid-connected inverter current control method, the invention provides an improved simple high-performance dead beat fractional order repetitive control method for controlling the grid-connected current, and the method has the following advantages:
1) and a weighted average current method is adopted, so that the control is simplified by reducing a three-order system to one order, and the control precision is not influenced.
2) A fractional order repetitive controller is embedded in the current control of the grid-connected inverter, under the condition that the sampling frequency is fixed, the maximum gain can still be obtained at the fundamental wave and each subharmonic even if the frequency of the power grid fluctuates, so that the repetitive controller can automatically adapt to the frequency fluctuation of the power grid, and the zero-static-error tracking can be realized on the fundamental wave and each subharmonic, therefore, the periodic interference and the approximate periodic interference can be effectively inhibited, the THD of the grid-connected current is reduced, and the current quality injected into the power grid is improved.
3) The dead-beat current control based on the weighted current simplifies the design of a control system, can quickly and accurately track a given signal, can automatically track the fluctuation of the reference frequency of the power grid by fractional order repetitive control, eliminates steady-state error, and can effectively improve the dynamic and static performances of the grid-connected current by combining the two.
4) The three-phase four-bridge-arm grid-connected inverter is directly decoupled into three independent single-phase loops, so that the design is simplified, and the control method is also suitable for the single-phase grid-connected inverter.
According to the attached drawing 1, values of parameters in the attached drawing 1 refer to an attached table 1, a topological graph of a three-phase four-leg grid-connected inverter can be decoupled into three independent single-phase grid-connected inverter controls, and a block diagram of weighted current of each phase in an S domain is shown in fig. 3.
Thus, the transfer functions of the inversion side current and the grid-connected side current of the LCL filter relative to the inversion side output voltage are as follows:
Figure BDA0002207732460000071
wherein the content of the first and second substances,
Figure BDA0002207732460000072
definition L ═ L1+L2Sum weighting factor α ═ L1By substituting the formula (1) with the formula/L, the following third-order transfer function can be obtained.
Figure BDA0002207732460000073
Defining the weighted average inductor current as:
I(s)＝αI1(s)+(1-α)I2(s) (3)
substituting equation (2) into equation (3) can obtain a first-order model of the controlled object as follows:
Figure BDA0002207732460000081
as described above, the design of the controller can be simplified by reducing the third-order system to the first order by weighting the average inductor current.
For the first order model described by equation (4), there are
Figure BDA0002207732460000082
Wherein v isjAnd vgjRespectively the inverter side voltage and the grid voltage ijIs the weighted average inductor current.
The discrete state equation of the grid-connected current at the next moment can be obtained by adopting forward difference as
Figure BDA0002207732460000083
Where j is a, b, c, if a zero-difference tracking of the grid-connected current to a given reference current is achieved within one sampling period, i (k +1) is i*(k) Then, the deadbeat control effect is considered to be achieved, and then the expression of the output voltage of the inverter side during the deadbeat control can be obtained as follows:
Figure BDA0002207732460000084
considering the computation delay and the system delay, the computation delay can be expressed as z-1If the system delay time is TdThen the delay function can be expressed as
Figure BDA0002207732460000085
The delay can be approximated as Td≈m·TsWhere m is an integer, using bilinear transformation has
Figure BDA0002207732460000086
The block diagram of the system under the control of DB is shown in FIG. 4, where K is the predicted inductance. Discretizing the controlled object by adopting a zero-order retainer can obtain the following steps:
Figure BDA0002207732460000087
the open loop transfer function of the system of fig. 4 is:
Figure BDA0002207732460000088
the root locus of the system obtained according to the open-loop transfer function is shown in fig. 5, and the upper value limit of K under different delay beats can be obtained according to the root locus.
The design method of the fractional order repetitive controller with frequency adaptation is as follows:
when the sampling frequency is fixed to fsWhen the grid frequency fluctuates within a certain range (50 +/-1 Hz), N is fs/f0Not necessarily an integer, andwherein N isDIs an integer, M is a fractional part, and lagrange is adopted to approximate z-MIs provided withWherein the Lagrangian coefficient is
Figure BDA0002207732460000093
k,i＝0,1,2,…n。
The amplitude-frequency response of the conventional integer order repetitive controller when the grid frequency fluctuates is shown in fig. 6, and it can be seen that when the grid frequency deviates from 50Hz, the gain of the conventional integer order repetitive controller at the fundamental wave and each harmonic is greatly reduced. When the power grid frequency fluctuates from 50Hz to 50 +/-0.4 Hz, the value N fluctuates within the range of 400 to 400 +/-3.2, the amplitude-frequency response at the 7 th harmonic wave is shown in FIG. 7 by adopting the traditional integer order repetitive control (N is 400) and the fractional order repetitive control (N is 400 +/-3.2), and it can be seen that when the power grid frequency deviates from 50Hz, the gain of the traditional integer order repetitive control at the harmonic wave is greatly reduced, so that the traditional integer order repetitive control is easily influenced by the power grid frequency fluctuation to cause the reduction of the tracking accuracy. The fractional order repetitive controller can follow the frequency fluctuation of the power grid, and ensures that the maximum gain is obtained at each harmonic, thereby improving the tracking precision of the system.
In order to improve the performance of the repetitive controller,selecting zero phase shift low pass filter Q (z) ═ a0z+a1+a0Z, wherein 2a0+a1Design the convergence coefficient K of repetitive control as 1rcRegulating KrcCan change the misconvergence speed, K, of the repetitive controllerrcThe larger the error the faster it converges.
The design of the compensation link can select the optimal compensation beat number according to the controlled object model, the grid voltage is regarded as disturbance, and the grid-connected current relative to the input voltage v of the inversion side is obtainedjThe transfer function of(s) is:
Figure BDA0002207732460000094
equation (9) is an actual controlled object when the controller is designed, and the transfer function of the controlled object obtained by substituting and discretizing the parameters in attached table 1 is:
Figure BDA0002207732460000095
if the coefficient K in the dead-beat control is selected to be 0.5, the formula (5) is substituted to obtain the closed-loop transfer function of the system as
Figure BDA0002207732460000096
In order to compensate the lag of the controlled object, a compensation link G is addedf(z)＝zpFIG. 8 shows G (z) Gf(z) a bode diagram with different linear phase lead compensation beats, wherein the lead compensation beats do not change amplitude-frequency characteristics, but the phase-frequency characteristics are obviously changed, when p is 2, the system bandwidth is maximum, the sampling and control delay is comprehensively considered, and p is 3 in experimental control.
A fractional order repetitive controller link is designed according to fig. 2 and connected in parallel with dead-beat control based on weighted inductor current. The designed repetitive controller is embedded into the deadbeat control. Comparing the simulation graphs of the dead-beat control integer-order weight control (shown in fig. 9) and the fractional-order repeat control (shown in fig. 10), it is clear that the steady-state error of the dead-beat fractional-order repeat control is smaller.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. A grid-connected inverter current control method is characterized by being realized by an electric energy storage component, an LCL type three-phase four-leg power conversion inverter circuit and a controller, wherein the controller inverts direct current of the electric energy storage component into alternating current by controlling the on and off of an insulated gate bipolar transistor in the LCL type three-phase four-leg power conversion inverter circuit, and the alternating current is merged into a power grid through a filter circuit and a grid-connected relay; the controller includes: a dead-beat predictive controller and a fractional order repetitive controller based on the weighted average inductor current; the grid-connected inverter current control method comprises the following steps:
decoupling the three-phase four-bridge-arm power conversion inverter circuit into three independent single-phase loops for control, introducing weighted current dead-beat control, and converting a three-order object into a first-order model;
introducing a predicted inductance coefficient as a ratio of a predicted inductance value and an actual inverter side inductance value in a control algorithm;
embedding the fractional order repetitive controller into a control algorithm of the weighted current dead-beat control to form dead-beat frequency self-adaptive control;
the controller collects the voltage phase of the power grid in real time, calculates the reference value of grid-connected current at the next moment according to the voltage phase, sends an error signal into the controller, obtains and normalizes an output voltage control value at an inversion side, and controls the on and off of the insulated gate bipolar transistor through pulse width modulation.
2. The grid-connected inverter current control method according to claim 1, wherein the introducing of the weighted current dead-beat control comprises selecting a weighting coefficient as a ratio of an inverter-side inductance to a sum of two inductances, i.e., the weighting coefficient α is L1/(L1+L2) The feedback current is a weighted average value of the inverter side inductive current and the grid-connected side inductive current, i is α i1+(1-α)i2The third order system is reduced to the first order by introducing a weighted average inductor current.
3. The grid-connected inverter current control method according to claim 1, wherein the introduced prediction inductance K is a number smaller than 1, and a value range of the prediction inductance K is determined by using a root trajectory for a delay beat number of a controlled object.
4. The grid-connected inverter current control method according to claim 1,
the fractional order repetitive controller is connected with the dead beat controller in parallel;
the fractional order repetitive controller GrcThe design of (z) specifically comprises:
approximating fractional order delay by Lagrange interpolation, noting the sampling frequency as fsGrid frequency of f0When f is0When the change is in a small range, the notation N ═ fs/f0＝ND+M，NDIs an integer part, M is a fractional part,
Figure FDA0002207732450000021
approximation of fractional order delay using lagrange interpolation
Figure FDA0002207732450000022
Delay each term coefficient of
Figure FDA0002207732450000023
Introducing a repetitive control coefficient K into fractional order repetitive controlrcIntroducing a low-pass filter Q (z) a without phase offset0z+a1+a0Z, wherein 2a0+a1＝1；
The linear phase lead compensation module is introduced into the fractional order repetitive control and is Gf(z)＝zpAdvance compensation of beat number
Figure FDA0002207732450000024
5. The grid-connected inverter current control method according to claim 1, wherein the electric energy storage component is an electric vehicle or a storage battery.
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Cited By (3)

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CN111769563A (en) * 2020-04-21 2020-10-13 闽南理工学院 LCL active power filter model and prediction control method thereof
CN113517710A (en) * 2021-06-16 2021-10-19 武汉理工大学 Electric vehicle V2G inversion control method and system based on state observer
CN113809734A (en) * 2021-09-22 2021-12-17 安徽工业大学 Distributed DC power supply inter-system cooperative current sharing control method

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