CN113541186A - Double closed-loop control method and system for single-phase LC type grid-connected inverter - Google Patents

Double closed-loop control method and system for single-phase LC type grid-connected inverter Download PDF

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CN113541186A
CN113541186A CN202110784687.2A CN202110784687A CN113541186A CN 113541186 A CN113541186 A CN 113541186A CN 202110784687 A CN202110784687 A CN 202110784687A CN 113541186 A CN113541186 A CN 113541186A
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grid
phase
signal
voltage
current
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赵庆生
徐国栋
李珍瑜
郭尊
原敏宏
韩肖清
郭贺宏
原帅
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Taiyuan University of Technology
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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
    • 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
    • H02M7/539—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 with automatic control of output wave form or frequency
    • H02M7/5395—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 with automatic control of output wave form or frequency by pulse-width modulation
    • 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
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers
    • 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

Abstract

The invention belongs to the technical field of power inverter control, and discloses a double closed-loop control method and a double closed-loop control system for a single-phase LC type grid-connected inverter, wherein the method comprises the following steps: s101, comparing the DC side voltage reference value VdAnd actual value VdCalculating a difference, and obtaining a secondary side filter inductor current amplitude according to the voltage difference; s102: taking voltage signal V of power gridsObtaining a standard unit sine signal sin ω t through a phase-locked loop PLL; s103: multiplying the secondary side filter inductance current amplitude signal by the unit sine signal to obtain an inductance current standard reference value and an inductance current actual value ILMaking a difference, and obtaining a modulation signal according to the inductance current difference; s104: the modulated signal is input to an SPWM module,and obtaining four driving signals to control the turn-off and the turn-on of a single-phase LC type grid-connected inverter switching device. The invention has stronger harmonic suppression capability and can greatly reduce the harmonic content of grid-connected current.

Description

Double closed-loop control method and system for single-phase LC type grid-connected inverter
Technical Field
The invention relates to a double closed-loop control method and a double closed-loop control system for a single-phase LC type grid-connected inverter, and belongs to the technical field of power inverter control.
Background
The problems of environmental pollution and energy crisis in the current society are increasingly prominent, and high-proportion renewable clean energy resources represented by photovoltaic and wind power are combined into a grid to become a key technology for solving the environmental pollution problem in the current society, optimizing an energy structure and constructing a strong smart power grid. However, the new energy also has negative effects, the renewable energy power generation has randomness and intermittency, and the use of a large number of nonlinear power electronic devices brings complex harmonic problems to the power grid, and how to reduce the harmonic content and realize high-efficiency and high-quality grid connection becomes a problem of wide attention of the current society.
The grid-connected inverter is important power equipment for new energy to be incorporated into a large power grid, and can effectively convert electric energy of the new energy into alternating current capable of being connected into the power grid. The control technology of the inverter mainly comprises the following steps: proportional-integral control, proportional resonance control, hysteresis current control, repetitive control, sliding mode control and the like. Each control method has advantages and limitations, for example, a conventional PR (Proportional resonance) controller can track a specified frequency signal well, but when the frequency fluctuates, the control system has a poor effect, and considering that the grid frequency fluctuates in the engineering practice, the conventional PR controller cannot meet the requirements. In order to obtain a better harmonic signal suppression and improve the grid-connected waveform quality, the dual-loop control is a common method. Therefore, the research on the double closed-loop control of the single-phase LC grid-connected inverter has important theoretical and practical significance.
Disclosure of Invention
The invention overcomes the defects of the prior art, and solves the technical problems that: a double closed-loop control system and method for a single-phase LC grid-connected inverter are provided.
In order to solve the technical problems, the invention adopts the technical scheme that: a double closed-loop control method for a single-phase LC grid-connected inverter comprises the following steps:
s101, comparing the DC side voltage reference value VdAnd actual value VdCalculating a difference, and obtaining a secondary side filter inductor current amplitude according to the voltage difference;
s102: taking voltage signal V of power gridsObtaining a standard unit sine signal sin ω t through a phase-locked loop PLL;
s103: multiplying the secondary side filter inductance current amplitude signal by the unit sine signal to obtain an inductance current standard reference value and an inductance current actual value ILMaking a difference, and obtaining a modulation signal according to the inductance current difference;
s104: and the modulation signal is input into the SPWM module to obtain four driving signals to control the turn-off and turn-on of a switching device of the single-phase LC grid-connected inverter.
In the step S101, the reference value V of the dc side voltage is obtained by the outer loop controller PIdAnd actual value VdConverting the difference value into a secondary side filter inductance current amplitude value;
the outer loop controller PI comprises a proportional-integral controller and a low-pass filter, the transfer function G of whichv(s) satisfies the following formula;
Figure BDA0003158262720000021
wherein, KPProportional coefficient of proportional integral controller; kIIs an integral coefficient; omegapFor the characteristic angular frequency of the low-pass filter, s represents the complex parameter.
The proportional coefficient K of the proportional integral controllerPTake 2.78, integral coefficient KIGet 83.33, low pass filterCharacteristic angular frequency ω ofpTake 150 rad/s.
In the step S103, the inductor current standard reference value and the inductor current actual value I are obtained by the inner loop quasi-proportional resonant controller QPRLIs quasi-converted into modulation information, the transfer function G of the inner-loop quasi-proportional resonant controller QPRQPR(s) satisfies the following formula:
Figure BDA0003158262720000022
wherein k ispProportional control gain; k is a radical of1、knIs a proportional resonance coefficient; omegacTo cut-off frequency, ωoFor the angular frequency of the power grid, h represents an odd harmonic, h is 3, 5 and 7, and s represents a complex parameter variable.
In the double closed-loop control method for the single-phase LC grid-connected inverter, h is 3, and the proportional control gain k ispTaking 50, the proportional resonance coefficient k1、k310 and 15, respectively, cut-off frequency omegacTaking 10rad/s, the angular frequency omega of the power gridoTake 314 rad/s.
In addition, the invention also provides a double closed-loop control system of the single-phase LC type grid-connected inverter, which is used for realizing the control method and comprises an LC filter, a first subtracter, a second subtracter, a multiplier, an inner loop quasi-proportional resonant controller QPR, an outer loop controller PI, a phase-locked loop PLL and an SPWM module, wherein the LC filter is arranged on the side of the alternating current power grid;
the first subtracter is used for comparing a direct current side voltage reference value VdAnd actual value VdCalculating a difference, wherein the outer loop controller PI is used for obtaining a secondary side filter inductance current amplitude according to the difference;
the phase-locked loop PLL is used for obtaining a standard unit sine signal sin ω t according to a power grid voltage signal Vs;
the multiplier is used for multiplying a secondary side filter inductance current amplitude signal by a unit sine signal to obtain an inductance current standard reference value, and the second subtracter is used for multiplying the inductance current standard reference value obtained by the multiplier and an inductance current actual value ILMaking a difference;
the inner loop quasi-proportional resonant controller QPR is used for controlling the current according to the standard reference value of the inductive current and the actual value I of the inductive currentLObtaining a modulation signal;
and the SPWM module is used for obtaining a driving signal according to the modulation signal and controlling the turn-off and the turn-on of a switching device of the single-phase LC grid-connected inverter.
The phase locked loop PLL uses the voltage V of the mainsSThe sampled Vmsin ω t signal is delayed by 1/4 periods to obtain a Vmccos ω t signal, which is then combined with the generated synchronous signal cos ω t1t and sin ω1t are multiplied respectively and then added to obtain an error e;
e＝Vm(sinωtcosω1t-cosωtsinω1t)；
where Vm and ω represent the peak voltage and angular frequency, ω, respectively, obtained from the AC side1Representing the actual angular frequency of the grid voltage Vs.
The LC filter comprises an inductor L and a filter capacitor C2。
The double closed-loop control system of the single-phase LC type grid-connected inverter further comprises a voltage sampling unit, an inductive current sampling unit and a power grid voltage sampling unit;
the voltage sampling unit is used for acquiring the actual value V of the direct current voltage at the direct current sided；
The inductive current sampling unit is used for collecting an actual value I of the inductive currentL；
The grid voltage sampling unit is used for collecting and acquiring a grid voltage signal Vs。
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a double closed-loop control method of a single-phase LC type grid-connected inverter, wherein when the single-phase LC type grid-connected inverter runs in no-load and light load, the power at the direct current side can meet the load, meanwhile, the energy can be fed into a power grid, and when the load is heavier, the power generated by the power grid can be supplied to the load. Compared with the existing grid-connected inverter control strategy, the method provided by the invention has the advantages that on the premise of ensuring a high power factor, the harmonic suppression capability is obviously improved, and the harmonic content of grid-connected current can be greatly reduced.
Drawings
Fig. 1 is a schematic structural diagram of a single-phase LC-type grid-connected inverter dual closed-loop control system according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a structure of an inner ring quasi-proportional resonant controller according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a connection between an outer loop controller PI and a phase locked loop and an inner loop quasi-proportional resonant controller according to an embodiment of the present invention;
FIG. 4 is a block diagram of a phase locked loop PLL according to an embodiment of the present invention;
FIG. 5 is a DC side voltage waveform diagram;
FIG. 6 is a waveform diagram illustrating voltage and current simulation outputted by the control system according to the first embodiment of the present invention;
fig. 7 is a waveform diagram of voltage and current output by the control system according to the first embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
As shown in fig. 1, an embodiment of the present invention provides a dual closed-loop control system for a single-phase LC-type grid-connected inverter, including an LC filter, a first subtractor, a second subtractor, a multiplier, an inner-loop quasi-proportional resonant controller QPR, an outer-loop controller PI, a phase-locked loop PLL, and an SPWM module, where the LC filter is disposed on an ac power grid side. VdIs a direct current voltage; c1A direct current side voltage stabilizing capacitor; S1-S4 are switching tubes IGBT of the grid-connected inverter; i isoOutputting current for the inverter; vcIs the LC filter capacitor voltage; i issIs the grid-connected current; i isLIs an inductive powerA stream; vsIs the grid voltage.
The LC filter comprises an inductor L and a filter capacitor C2。
Further, the double closed-loop control system of the single-phase LC-type grid-connected inverter of the embodiment further comprises a voltage sampling unit, an inductive current sampling unit and a grid voltage sampling unit; the voltage sampling unit is used for acquiring the actual value V of the direct current voltage at the direct current sided(ii) a The inductive current sampling unit is used for collecting an actual value I of the inductive currentL(ii) a The grid voltage sampling unit is used for collecting and acquiring a grid voltage signal Vs。
Specifically, in this embodiment, the first subtractor is used for comparing the dc-side voltage reference value VdAnd actual value VdCalculating a difference, wherein the outer loop controller PI is used for obtaining a secondary side filter inductance current amplitude according to the difference; the phase-locked loop PLL is used for obtaining a standard unit sine signal sin ω t according to a power grid voltage signal Vs; the multiplier is used for multiplying a secondary side filter inductance current amplitude signal by a unit sine signal to obtain an inductance current standard reference value, and the second subtracter is used for multiplying the inductance current standard reference value obtained by the multiplier and an inductance current actual value ILMaking a difference; the inner loop quasi-proportional resonant controller QPR is used for controlling the current according to the standard reference value of the inductive current and the actual value I of the inductive currentLObtaining a modulation signal; and the SPWM module is used for obtaining a driving signal according to the modulation signal and controlling the turn-off and the turn-on of a switching device of the single-phase LC grid-connected inverter.
Specifically, in the present embodiment, the transfer function G of the inner-loop quasi-proportional resonant controller QPRQPR(s) satisfies the following formula:
Figure BDA0003158262720000051
wherein s represents a complex parameter, kpThe dynamic characteristic of the controller system can be improved by proportional control gain; 2k1ωcs/(s2+2ωcs+ωo 2) For resonant terms, the function is to realizeError-free tracking of the controller 50Hz base frequency signal; omega0Is the grid angular frequency; 2knωcs/(s2+2ωcs+ωo 2) For the harmonic suppression term, harmonic (mainly 3, 5 and 7) signals can be suppressed; k is a radical of1、knIs a proportional resonance coefficient; omegacThe bandwidth is adjusted for the cut-off frequency, h represents the odd harmonics (mainly 3, 5, 7 times depending on the actually existing harmonic order).
Further, in this embodiment, the order h of the quasi-proportional resonant controller is 3, that is, the summation term in equation (1) is only n-3, and the proportional control gain k ispTaking 50, the proportional resonance coefficient k1、k310 and 15 respectively, 10rad/s for the cut-off frequency and 314rad/s for the grid angular frequency.
FIG. 2 shows a schematic diagram of an inner-loop quasi-proportional resonant controller QPR employed in the present embodiment, where k issAnd kvCurrent and voltage sensing gains, k, respectivelypwmIs the modulation gain, G, of pwmQPRIs a transfer function that improves quasi-proportional resonance control. Wherein ioRepresenting inverter output current times ksValue of (a), ioDenotes a given reference value of the output current, IoIndicating the output current of the inverter, VoDenotes the reference value of the output voltage, VconRepresenting the value of the modulation voltage.
Specifically, in this embodiment, the outer loop controller PI includes a proportional-integral controller and a low-pass filter, and fig. 3 shows a connection schematic diagram of the outer loop controller PI with a phase-locked loop and an inner loop quasi-proportional resonant controller;
transfer function G of outer loop controller PIv(s) satisfies the following formula:
Figure BDA0003158262720000052
wherein s represents a complex parameter, KPProportional coefficient of proportional integral controller; kIIs an integral coefficient; omegapIs the characteristic angular frequency of the low pass filter.
Specifically, in the present embodiment, the proportional coefficient K of the proportional-integral controller in the outer loop controller PIPTake 2.78, integral coefficient KITaking 83.33, low-pass filter characteristic angular frequency omegapTake 150 rad/s.
As shown in fig. 4, a schematic block diagram of the circuit of the phase-locked loop PLL of the present embodiment is shown, wherein the phase-locked loop circuit utilizes the mains voltage VsObtaining a signal V after samplingm sinωt，VmAnd ω represents a voltage peak value and an angular frequency obtained from the ac side, respectively. After 1/4 period delay, the signal-V is obtainedmcos ω t. The two signals are then combined with a synchronization signal cos omega generated thereafter1t and sin ω1t are multiplied respectively and then added to obtain an error e, namely the expression of the error e is as follows:
e＝Vm(sinωtcosω1t-cosωtsinω1t)；(3)
where ω denotes the standard fundamental angular frequency, ω1Representing the corresponding angular frequency of the grid voltage signal Vs.
Further, simulation studies were conducted on the proposed embodiment of the present invention, as shown in table 1 below, which lists the system specifications of the simulation, and simulation and experimental evaluation were conducted on the proposed control system in table 1.
Table 1 simulation system parameter list
Parameter(s) Numerical value
Voltage V at DC sidedc/V 70
DC side capacitor Cdc/μF 330
Filter inductance L/mH 0.6
Filter capacitor C/mu F 10
AC side parallel voltage Vs/V 40
Frequency f of the grid0/Hz 50
Sampling frequency fs/kHz 15
Simulation and experimental evaluation are as follows:
fig. 5 is a waveform diagram of a dc side voltage simulation according to an embodiment of the present invention, and fig. 5 shows: the dc side contains a dc signal and also a frequency-doubled ac harmonic signal.
FIG. 6 is a waveform diagram of simulation of output voltage and current according to an embodiment of the present invention, and FIG. 6 shows: the improved double-loop control grid-connected current waveform based on the Q-PR controller is good in sine degree. Through harmonic content analysis, the output current THD is 2.67% under the improved double-loop control based on the Q-PR controller, the harmonic suppression capability is strong, and the harmonic content of grid-connected current can be greatly reduced.
By adjusting the load, the power flow direction of the whole system is observed. The load carried by the embodiment of the invention is a linear load, when the load carried by the embodiment is no-load, all the power generated at the direct current side is fed into a power grid, and the power is 63.6w obtained by a power meter; when a load (42 omega) with 1/3 operates, the power consumed by the load is 37.9w, and the power generated by the direct current side can meet the requirement of the load, and 26w is fed into a power grid; when a load belt 2/3 is operated by load (84 omega), the power consumed by the load is 74.5w, the power emitted by the direct current side cannot meet the consumption of the load, and the power grid is complemented to 10.85 w; when the load is running fully (126 Ω), the power consumed by the load is 110.7w, except for the power emitted from the dc side, which now requires 47.25w of power to be supplied by the grid. Through the analysis, when the power grid runs in a no-load or light-load mode, the power at the direct current side can meet the load, meanwhile, the energy can be fed into the power grid, and when the load is heavy, the power grid is required to generate power to supply the load.
FIG. 7 shows the output voltage V of the experiment according to the embodiment of the present inventionsOutput current IoWaveform diagram, fig. 7 shows: the output voltage and current of the improved double-loop control based on the inner-loop quasi-proportional resonant controller QPR can achieve synchronization and have better sine degree.
Example two
The embodiment of the invention provides a double closed-loop control method for a single-phase LC type grid-connected inverter, which comprises the following steps:
s101, comparing the DC side voltage reference value VdAnd actual value VdCalculating a difference, and obtaining a secondary side filter inductor current amplitude according to the voltage difference;
s102: taking voltage signal V of power gridsObtaining a standard unit sine signal sin ω t through a phase-locked loop PLL;
s103: multiplying the secondary side filter inductance current amplitude signal by the unit sine signal to obtain an inductance current standard reference value and an inductance current actual value ILMaking a difference, and obtaining a modulation signal according to the inductance current difference;
s104: and the modulation signal is input into the SPWM module to obtain four driving signals to control the turn-off and turn-on of a switching device of the single-phase LC grid-connected inverter.
Specifically, in step S101, the reference value V of the dc-side voltage is obtained by the outer loop controller PIdAnd actual value VdConverting the difference value into a secondary side filter inductance current amplitude value; the outer loop controller PI includes a proportional-integral controller and a low-pass filter, and the structure and parameters thereof are the same as those of the first embodiment.
Specifically, in the step S103, the methodThe quasi-proportional resonant controller QPR of the inner loop converts the standard reference value of the inductive current and the actual value I of the inductive currentLThe difference value of (a) is converted into modulation information, and the structure and parameters of the inner-loop quasi-proportional resonant controller QPR are the same as those of the first embodiment.
In particular, in this embodiment, the phase locked loop PLL utilizes the voltage V to the mainsSThe sampled Vmsin ω t signal is delayed by 1/4 periods to obtain a Vmccos ω t signal, which is then combined with the generated synchronous signal cos ω t1t and sin ω1And t are multiplied respectively and then added to obtain an error e, and the structure and parameters of the phase-locked loop PLL are the same as those of the first embodiment.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A double closed-loop control method for a single-phase LC grid-connected inverter is characterized by comprising the following steps:
s101, comparing the DC side voltage reference value VdAnd actual value VdCalculating a difference, and obtaining a secondary side filter inductor current amplitude according to the voltage difference;
s102: taking voltage signal V of power gridsObtaining a standard unit sine signal sin ω t through a phase-locked loop PLL;
s103: multiplying the secondary side filter inductance current amplitude signal by the unit sine signal to obtain an inductance current standard reference value and an inductance current actual value ILMaking a difference, and obtaining a modulation signal according to the inductance current difference;
s104: and the modulation signal is input into the SPWM module to obtain four driving signals to control the turn-off and turn-on of a switching device of the single-phase LC grid-connected inverter.
2. The method according to claim 1, wherein in step S101, the reference value V of the dc-side voltage is obtained by an external loop controller PIdAnd actual value VdConverting the difference value into a secondary side filter inductance current amplitude value;
the outer loop controller PI comprises a proportional-integral controller and a low-pass filter, the transfer function G of whichv(s) satisfies the following formula;
Figure DEST_PATH_IMAGE002
；
wherein the content of the first and second substances,K P proportional coefficient of proportional integral controller;K I is an integral coefficient; omegapIs the characteristic angular frequency of the low-pass filter,srepresenting complex parametric variables.
3. The double closed-loop control method of the single-phase LC grid-connected inverter as claimed in claim 2, wherein the proportional coefficient of the proportional-integral controllerK P Take 2.78, integral coefficientK I Taking 83.33, the characteristic angular frequency omega of the low-pass filterpTake 150 rad/s.
4. The method according to claim 1, wherein in step S103, the inductor current standard reference value and the inductor current actual value I are determined by an inner loop quasi-proportional resonant controller QPRLIs converted into modulation information, the transfer function of the inner-loop quasi-proportional resonant controller QPRG QPR(s) satisfies the following formula:
Figure DEST_PATH_IMAGE004
；
wherein the content of the first and second substances,k p proportional control gain;k 1、k nis a proportional resonance coefficient; omegacTo cut-off frequency, ωoFor grid angular frequency, h stands for odd harmonics, h =3, 5, 7,srepresenting complex parametric variables.
5. The single-phase LC type grid-connected inverter double closed-loop control method according to claim 4, characterized in that h =3, proportional control gaink p Taking 50, proportional resonance coefficientk 1、k 310 and 15, respectively, cut-off frequency omegacTaking 10rad/s, the angular frequency omega of the power gridoTake 314 rad/s.
6. A single-phase LC type grid-connected inverter double closed-loop control system is used for realizing a control method according to any one of claims 1 to 5, and is characterized by comprising an LC filter, a first subtracter, a second subtracter, a multiplier, an inner loop quasi-proportional resonant controller QPR, an outer loop controller PI, a phase-locked loop PLL and an SPWM module, wherein the LC filter is arranged on the side of an alternating current power grid;
the first subtracter is used for comparing a direct current side voltage reference value VdAnd actual value VdCalculating a difference, wherein the outer loop controller PI is used for obtaining a secondary side filter inductance current amplitude according to the difference;
the phase-locked loop PLL is used for obtaining a standard unit sine signal sin ω t according to a power grid voltage signal Vs;
the multiplier is used for multiplying a secondary side filter inductance current amplitude signal by a unit sine signal to obtain an inductance current standard reference value, and the second subtracter is used for multiplying the inductance current standard reference value obtained by the multiplier and an inductance current actual value ILMaking a difference;
the inner loop quasi-proportional resonant controller QPR is used for controlling the current according to the standard reference value of the inductive current and the actual value I of the inductive currentLObtaining a modulation signal;
and the SPWM module is used for obtaining a driving signal according to the modulation signal and controlling the turn-off and the turn-on of a switching device of the single-phase LC grid-connected inverter.
7. The system of claim 6, wherein the phase locked loop PLL utilizes a reference voltage V to the utility voltageSThe Vmsin ω t signal obtained after sampling is delayed for 1/4 periods to obtain the Vmscos ω t signal, which is then combined with the generated synchronous signal cosω 1t and sinω 1t are multiplied respectively and then added to obtain an error e;
Figure DEST_PATH_IMAGE006
；
where Vm and ω represent the peak voltage and angular frequency, ω, respectively, obtained from the AC side1Representing the actual angular frequency of the grid voltage Vs.
8. The single-phase LC type grid-connected inverter double closed-loop control system according to claim 6, characterized in that the LC filter comprises an inductorLAnd a filter capacitorC 2。
9. The single-phase LC type grid-connected inverter double closed-loop control system according to claim 6, characterized by further comprising a voltage sampling unit, an inductive current sampling unit and a grid voltage sampling unit;
the voltage sampling unit is used for acquiring the actual value V of the direct current voltage at the direct current sided；
The inductive current sampling unit is used for collecting an actual value I of the inductive currentL；
The grid voltage sampling unit is used for collecting and acquiring a grid voltage signal Vs。
CN202110784687.2A 2021-07-12 2021-07-12 Double closed-loop control method and system for single-phase LC type grid-connected inverter Pending CN113541186A (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105978018A (en) * 2015-12-16 2016-09-28 许昌学院 LC grid-connected inverter control method
TWI604697B (en) * 2016-12-02 2017-11-01 國家中山科學研究院 Phase-locked loop method for a utility parallel system
CN107834879A (en) * 2017-10-12 2018-03-23 安徽华腾电气有限公司 The vector control method of single-phase off-network inverter
CN109193794A (en) * 2018-09-22 2019-01-11 东北电力大学 A kind of Grid-connected Control Strategy of low-voltage direct micro-capacitance sensor
CN110138253A (en) * 2019-06-28 2019-08-16 盐城正邦环保科技有限公司 A kind of photovoltaic combining inverter control method that multi-resonant PR and PI jointly controls
CN111740635A (en) * 2020-07-24 2020-10-02 武汉海德博创科技有限公司 Double-loop control method of single-phase LC inverter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105978018A (en) * 2015-12-16 2016-09-28 许昌学院 LC grid-connected inverter control method
TWI604697B (en) * 2016-12-02 2017-11-01 國家中山科學研究院 Phase-locked loop method for a utility parallel system
CN107834879A (en) * 2017-10-12 2018-03-23 安徽华腾电气有限公司 The vector control method of single-phase off-network inverter
CN109193794A (en) * 2018-09-22 2019-01-11 东北电力大学 A kind of Grid-connected Control Strategy of low-voltage direct micro-capacitance sensor
CN110138253A (en) * 2019-06-28 2019-08-16 盐城正邦环保科技有限公司 A kind of photovoltaic combining inverter control method that multi-resonant PR and PI jointly controls
CN111740635A (en) * 2020-07-24 2020-10-02 武汉海德博创科技有限公司 Double-loop control method of single-phase LC inverter

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Application publication date: 20211022