CN114915195A - Grid-connected harmonic suppression method based on single-phase current source type five-level inverter - Google Patents

Grid-connected harmonic suppression method based on single-phase current source type five-level inverter Download PDF

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CN114915195A
CN114915195A CN202111542621.9A CN202111542621A CN114915195A CN 114915195 A CN114915195 A CN 114915195A CN 202111542621 A CN202111542621 A CN 202111542621A CN 114915195 A CN114915195 A CN 114915195A
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鲍建宇
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Ningbo University of Technology
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    • 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
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • 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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • 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)
  • Control Of Electrical Variables (AREA)

Abstract

The invention relates to a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter, which is used for sampling capacitor voltage u c To obtain the capacitor voltage u c Fundamental component u of cb (ii) a Judging a grid-connected mode through a high-frequency harmonic current compensation circuit, and selecting a feedback current i to be constructed according to the grid-connected mode RC (ii) a The obtained sine modulation signal i s * Into a multi-carrier PWM generator, thenAnd then controlling the on and off of each switching device in the single-phase current type five-level inverter circuit. The method performs resonance suppression aiming at an active mode, a reactive mode and the active and reactive modes, so that the effect of adjusting any power factor during grid connection is realized, the functions are rich, the applicability is wider, the method ensures high current response speed, further ensures the corresponding speed of the system, and improves the efficiency.

Description

Grid-connected harmonic suppression method based on single-phase current source type five-level inverter
Technical Field
The invention relates to the technical field of power electronic converters, in particular to a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter.
Background
Grid-connected inverters can be divided into voltage source type inverters and current source type inverters according to different energy storage elements on the direct current side of the inverters. At present, a grid-connected inverter generally adopts a voltage source type inverter, but a current source type inverter also has a plurality of advantages, such as prolonging the service life of a converter without adopting an electrolytic capacitor at an input end, having no through-current problem of a bridge arm and strong short-circuit protection capability. By adopting the current source type five-level inverter, the output current waveform can be closer to sine, and each switching device only needs to bear half of current stress, so that the performance and reliability of the circuit are effectively improved. However, the output side of the current source type inverter usually adopts capacitance filtering when grid connection is performed, because an equivalent inductance exists between a grid connection point and an inverter output point connecting line, when the inductance of the equivalent inductance just reaches the resonance with the inverter LC, a high-frequency resonance component is introduced into the grid voltage at the output side of the inverter, once the high-frequency component enters a control system through sampling, problems such as system divergence, inverter resonance and the like can be caused, and if no suppression is added, harmonic current of phase frequency can be infinitely amplified until the system is broken down.
In the prior art, the resonance of a voltage type grid-connected inverter is generally suppressed, and the suppression method is often only suitable for a pure active grid-connected mode, so that the power factor is not adjustable and the function is relatively single; in addition, the conventional resonance suppression method for the voltage-type inverter generally requires two-stage conversion processing of current and voltage, and has a complex structure and a slow current response speed.
Disclosure of Invention
The invention aims to solve the technical problem of resonance generated when a single-phase current source type five-level inverter is used for grid-connected inversion, and provides a grid-connected harmonic suppression method which can well suppress resonance, can adjust any power factor during grid connection and has high current response speed.
The invention adopts the technical scheme that a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter is implemented by a grid-connected system based on a small current-sharing inductance single-phase current type five-level inverter, the grid-connected system based on the small current-sharing inductance single-phase current type five-level inverter comprises a main circuit part and a control circuit part, the main circuit part comprises a single-phase current type five-level inverter circuit, a CLL filter circuit and a grid-side power circuit, the control circuit part comprises a phase-locked loop circuit, a single-phase alternating current coordinate transformation circuit, a PI-based direct current control circuit, a capacitor feedback voltage low-pass filter processing circuit, a high-frequency harmonic current compensation circuit, a grid-connected current reference signal circuit and a multi-carrier PWM generator driving circuit, the PI-based direct current control circuit comprises a first-stage PI regulator, the method comprises the following steps:
s1, collecting the voltage u of the power grid s As a reference signal, performing phase locking processing through a phase-locked loop circuit to obtain a reference phase angle theta, and respectively sending the reference phase angle theta into a coordinate conversion circuit of single-phase alternating current and a direct current control circuit based on PI (proportion integration) for alpha beta-dq conversion and dq-alpha beta conversion;
s2, collecting power grid current i s Carrying out alpha beta-dq conversion processing through a coordinate conversion circuit of the single-phase alternating current to obtain a direct current I under a dq coordinate system d And I q And applying a direct current I d And I q Sending the signal to a direct current control circuit based on PI as a negative feedback signal of a first-stage PI regulator;
s3, setting a theoretical value I d * And I q * ，I d * Representing the value of the active current to be injected into the grid, I q * Representing the value of the reactive current to be injected into the network, I d * And I q * Input into a PI-based direct current control circuit, and respectively connected with a negative feedback signal I d And I q Comparing to obtain respective current error signals, inputting the current error signals into a first-stage PI regulator for current conversion to obtain new d-q axis direct current I sd And I sq Then carrying out dq-alpha beta inverse transformation to obtain single-phase alternating current i sa ；
S4, sampling capacitor voltage u c Processed to obtain a capacitor voltage u c Fundamental component u of cb ；
S5, judging a grid-connected mode through given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and selecting feedback current i to be constructed according to the grid-connected mode RC (ii) a The specific process is as follows: when I d * ≠0、I q * When the voltage is equal to 0, namely the grid connection is carried out in a pure active mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I is d * ＝0、I q * When not equal to 0, namely grid connection is carried out in a pure reactive mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I d * ≠0、I q * When the voltage is not equal to 0, namely the grid connection is carried out in an active mode and a reactive mode, and the capacitor voltage u is selected c As a feedback current i RC ；
S6, obtaining a single-phase alternating current i sa Based on the harmonic compensation current i, the harmonic compensation current i is reversely injected into the direct current control circuit based on the PI RC With single-phase alternating current i sa Comparing to obtain new AC current i s ’ Obtaining a sinusoidal modulation signal i after amplitude per unit processing s * I.e. the grid-connected current reference signal;
s7, obtaining the sine modulation signal i s * And the signal is sent to a multi-carrier PWM generator to generate 8 paths of SPWM signals, and the SPWM signals are subjected to isolation driving to control the on and off of each switching device in the single-phase current type five-level inverter circuit.
The beneficial effects of the invention are: on the basis of a universal single-phase current type five-level inverter circuit topology, the current-sharing inductance value can be reduced from mH level to uH level through high-frequency modulation, and the practicability of the current type multi-level converter is effectively improved. The single-phase current source type five-level converter based on the uH level current-sharing inductor is used for grid-connected inversion, and the problem of harmonic self-resonance on the output side can be caused as in the traditional voltage type inverter. The invention not only solves the harmonic self-resonance problem in the pure active grid-connected mode (the power factor is 1) by adopting the high-frequency harmonic current compensation method, but also provides a resonance inhibition method in the pure reactive mode and the active and reactive modes, thereby realizing the effect of adjusting any power factor in the grid-connected mode. Therefore, the single-phase current source type five-level converter and the harmonic suppression strategy thereof are used for conventional grid-connected power generation, have a reactive compensation function, enrich the use functions of an inverter and have wider applicability; and the method is based on current direct control, the current response speed is high, the response speed of the system is further ensured, and the working efficiency is improved.
Preferably, in step S4, the capacitance voltage u is obtained through processing c Fundamental component u of cb The specific method comprises the following steps: sampling capacitor voltage u c To the capacitor voltage u c Sequentially carrying out alpha beta-dq conversion and dq-alpha beta conversion treatment to obtain direct current u under a dq coordinate system cd And u cq Then applying a DC current u cd And u cq Respectively processed by a low pass filter in a low pass filter processing circuit of the capacitor feedback voltage to respectively obtain u cd And u cq Fundamental component u of cdb And u cqb And then carrying out dq-alpha beta inverse transformation to obtain a capacitor voltage u c Fundamental component u of cb 。
Preferably, the high-frequency harmonic component is equal to the capacitor voltage u c And the fundamental component u cb The difference between them.
Drawings
Fig. 1 is a schematic diagram of a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter according to the present invention;
FIG. 2 shows a diagram of the present invention when setting I d * ＝15、I q * A grid-connected current waveform diagram when the current is 0;
FIG. 3 shows a diagram of the present invention when setting I d * ＝0、I q * A grid-connected current waveform diagram when the time is-19;
FIG. 4 shows the formula I in the present invention d * ＝15、I q * A grid-connected current waveform diagram when the time is-15;
as shown in the figure: 1. a single-phase current type five-level inverter circuit; 2. a CLL filter circuit; 3. a network-side power supply circuit; 4. a phase-locked loop circuit; 5. a coordinate conversion circuit for single-phase alternating current; 6. a PI-based direct current control circuit; 7. a low-pass filter processing circuit of the capacitor feedback voltage; 8. a high-frequency harmonic current compensation circuit; 9. a grid-connected current reference signal circuit; 10. a multicarrier PWM generator driving circuit.
Detailed Description
The invention is further described below with reference to the accompanying drawings in combination with specific embodiments so that those skilled in the art can practice the invention with reference to the description, and the scope of the invention is not limited to the specific embodiments.
The invention relates to a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter, which is implemented by a grid-connected system based on a small current-sharing inductance single-phase current type five-level inverter, the grid-connected system based on the small current-sharing inductance single-phase current type five-level inverter comprises a main circuit part and a control circuit part, as shown in figure 1, the main circuit part comprises a single-phase current type five-level inverter circuit 1, a CLL filter circuit 2 consisting of a filter capacitor and a lead wire equivalent inductor and a grid-side power circuit 3, the control circuit part comprises a phase-locked loop circuit 4, a single-phase alternating current coordinate transformation circuit 5, a PI-based direct current control circuit 6, a capacitor feedback voltage low-pass filter processing circuit 7, a high-frequency harmonic current compensation circuit 8, a grid-connected current reference signal circuit 9 and a multi-carrier PWM generator driving circuit 10, the direct current control circuit 6 based on PI comprises a one-stage PI regulator, and the method comprises the following steps:
s1, as shown in figure 1, collecting the voltage u of the power grid s As reference signal, the grid voltage u s The phase-locked processing is carried out through a phase-locked loop circuit 4 to obtain a reference phase angle theta, and the reference phase angle theta is respectively sent to a coordinate conversion circuit 5 of single-phase alternating current and a direct current control circuit 6 based on PI and is respectively used for alpha beta-dq conversion and dq-alpha beta conversion;
s2, collecting power grid current i s Grid current i s The coordinate transformation circuit 5 of the single-phase alternating current carries out alpha beta-dq transformation processing to obtain the direct current I under the dq coordinate system d And I q And applying a direct current I d And I q The signal is sent to a direct current control circuit 6 based on PI to be used as a negative feedback signal of a PI regulator;
s3, setting theoretical value I d * And I q * ，I d * Representing the value of the active current to be injected into the grid, I q * Representing the value of the reactive current to be injected into the network, I d * And I q * Input into a PI-based direct current control circuit 6, respectively connected with a negative feedback signal I d And I q Comparing to obtain respective current error signals, and passing the current error signals through PI regulator to obtain new d-q axis DC current I sd And I sq Then carrying out dq-alpha beta inverse transformation to obtain single-phase alternating current i sa ；
S4, sampling capacitor voltage u c Processed to obtain a capacitor voltage u c Fundamental component u of cb ；
S5, judging a grid-connected mode through given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and selecting harmonic feedback current i to be constructed according to the grid-connected mode RC ；u c And u cb For constructing harmonic feedback currents, I d * And I q * The method is used for judging the grid-connected working mode (pure active mode or reactive mode), and comprises the following specific processes: when I is d * ≠0、I q * When the voltage is equal to 0, namely the grid connection is carried out in a pure active mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I is d * ＝0、I q * When not equal to 0, namely grid connection is carried out in a pure reactive mode, and the capacitor voltage u is selected c As a feedback current i RC The high-frequency harmonic component is a capacitance voltage u c And the fundamental component u cb The difference between the two; when I is d * ≠0、I q * When the voltage is not equal to 0, namely the grid connection is carried out in an active mode and a reactive mode, and the capacitor voltage u is selected c As a feedback current i RC The high-frequency harmonic component is a capacitance voltage u c And the fundamental component u cb The difference between them.
S6, obtaining a single-phase alternating current i sa On the basis of the above-mentioned characteristics, by reversely injecting a harmonic compensation current i into the PI-based direct current control circuit 6 RC With single-phase alternating current i sa Comparing to obtain new AC current i s ’ Obtaining a sinusoidal modulation signal i after amplitude per unit processing s * I.e. the grid-connected current reference signal;
s7, obtaining the sine modulation signal i s * The signals are sent to a multi-carrier PWM generator driving circuit 10, eight paths of SPWM signals are generated through the multi-carrier PWM generator, and the on and off of each switching device in the single-phase current type five-level inverter circuit 1 are controlled after isolation driving.
On the basis of a universal single-phase current type five-level inverter circuit topology, the current-sharing inductance value can be reduced from mH level to uH level through high-frequency modulation, and the practicability of the current type multi-level converter is effectively improved. The single-phase current source type five-level converter based on the uH level current-sharing inductor is used for grid-connected inversion, and the problem of harmonic self-resonance on the output side can be caused as in the traditional voltage type inverter. The invention not only solves the harmonic self-resonance problem in the pure active grid-connected mode (the power factor is 1) by adopting a high-frequency harmonic current compensation method, but also provides a resonance inhibition method in the pure reactive mode and the active and reactive modes, thereby realizing the effect of adjusting any power factor in the grid-connected mode, and the specific effect is shown in the grid-connected current waveform shown in fig. 2, fig. 3 and fig. 4. Therefore, the single-phase current source type five-level converter and the harmonic suppression strategy thereof are used for conventional grid-connected power generation, have a reactive compensation function, enrich the use functions of an inverter and have wider applicability; and the method is based on current direct control, the current response speed is high, the response speed of the system is further ensured, and the working efficiency is improved.
In step S4, the processing results in the capacitor voltage u c Fundamental component u of cb The specific method comprises the following steps: sampling capacitor voltage u c To the capacitor voltage u c In turn, theCarrying out alpha beta-dq conversion and dq-alpha beta conversion processing to obtain direct current u under dq coordinate system cd And u cq Then applying a DC current u cd And u cq Respectively processed by a low pass filter in a low pass filter processing circuit 7 of the capacitor feedback voltage to respectively obtain u cd And u cq Fundamental component u of cdb And u cqb And then carrying out dq-alpha beta inverse transformation to obtain a capacitor voltage u c Fundamental component u of cb 。
The invention respectively carries out simulation verification aiming at three grid-connected working modes, (1) a pure active mode: setting I d * ＝15、I q * 0; (2) pure reactive mode: setting I d * ＝0、I q * -19; (3) active + reactive mode: setting I d * ＝15、I q * -15. For the sake of easy comparison of the control effect, when t is set to 0.1s, the feedback current signal for compensation is controlled. As shown in fig. 2, 3 and 4, it can be seen that: under three kinds of work modes of being incorporated into the power networks, the harmonic self-resonance problem of single-phase current type five level inverter circuit 1 output side can all be well restrained, and the current waveform of being incorporated into the power networks is close to the sine wave, can realize that arbitrary power factor is adjustable when being incorporated into the power networks simultaneously.
On the basis of a universal circuit topology, the current-sharing inductance value is reduced from mH level to uH level through high-frequency modulation, and the practicability of the current type multilevel converter is further improved. On the basis, the invention provides a current harmonic compensation method based on a small current-sharing inductance single-phase current type five-level inverter to solve the problem of harmonic self-resonance at the output side of the inverter, and 50H is obtained by sampling the voltage on a filter capacitor C and respectively carrying out alpha beta-dq conversion, low-pass filtering and dq-alpha beta inverse conversion treatment z And the voltage fundamental wave component is subtracted from the original capacitor voltage to obtain a high-frequency harmonic component, and the high-frequency harmonic component is utilized to carry out harmonic compensation on the grid-connected current. Under three different grid-connected working modes of pure active, pure reactive and active + reactive, the compensation method can achieve the effect of inhibiting resonance, and the specific effect is shown in grid-connected current waveforms shown in fig. 2, fig. 3 and fig. 4.

Claims (3)

1. A grid-connected harmonic suppression method based on a single-phase current source type five-level inverter is characterized by comprising the following steps: the method is implemented by a grid-connected system based on a small current-sharing inductance single-phase current type five-level inverter, the grid-connected system based on the small current-sharing inductance single-phase current type five-level inverter comprises a main circuit part and a control circuit part, the main circuit part comprises a single-phase current type five-level inverter circuit (1), a CLL filter circuit (2) and a grid-side power circuit (3), the control circuit part comprises a phase-locked loop circuit (4), a single-phase alternating current coordinate transformation circuit (5), a PI-based direct current control circuit (6), a low-pass filter processing circuit (7) of capacitance feedback voltage, a high-frequency harmonic current compensation circuit (8), a grid-connected current reference signal circuit (9) and a multi-carrier PWM generator driving circuit (10), the PI-based direct current control circuit (6) comprises a first-stage PI regulator, the method comprises the following steps:
s1, collecting the voltage u of the power grid s As reference signal, the grid voltage u s The phase-locked loop circuit (4) is used for performing phase-locked processing to obtain a reference phase angle theta, and the reference phase angle theta is respectively sent to a coordinate conversion circuit (5) of single-phase alternating current and a direct current control circuit (6) based on PI and is respectively used for alpha beta-dq conversion and dq-alpha beta conversion;
s2, collecting power grid current i s Grid current i s Alpha beta-dq conversion processing is carried out through a coordinate conversion circuit (5) of the single-phase alternating current to obtain direct current I under a dq coordinate system d And I q And applying a direct current I d And I q The signal is sent to a direct current control circuit (6) based on the PI to be used as a negative feedback signal of a PI regulator;
s3, setting a theoretical value I d * And I q * ，I d * Representing the value of the active current to be injected into the grid, I q * Representing the value of the reactive current to be injected into the network, I d * And I q * Input into a PI-based direct current control circuit (6) and respectively connected with a negative feedback signal I d And I q Comparing to obtain respective current error signals, and passing the current error signals through PI regulator to obtain new d-q axis DC current I sd And I sq Then carrying out dq-alpha beta inverse transformation to obtain single-phase alternating current i sa ；
S4, sampling capacitor voltage u c Processed to obtain a capacitor voltage u c Fundamental component u of cb ；
S5, judging a grid-connected mode through given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and selecting feedback current i to be constructed according to the grid-connected mode RC (ii) a The specific process is as follows: when I is d * ≠0、I q * When the voltage is equal to 0, namely the grid connection is carried out in a pure active mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I d * ＝0、I q * When not equal to 0, namely grid connection is carried out in a pure reactive mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I is d * ≠0、I q * When the voltage is not equal to 0, namely the grid connection is carried out in an active mode and a reactive mode, and the capacitor voltage u is selected c As a feedback current i RC ；
S6, obtaining a single-phase alternating current i sa Based on the above, by injecting a harmonic compensation current i in reverse direction into a PI-based direct current control circuit (6) RC With single-phase alternating current i sa Comparing to obtain new AC current i s ’ Obtaining a sinusoidal modulation signal i after amplitude per unit processing s * I.e. the grid-connected current reference signal;
s7, obtaining the sine modulation signal i s * The signal is sent into a multi-carrier PWM generator driving circuit (10), eight paths of SPWM signals are generated through the multi-carrier PWM generator, and the switching-on and switching-off of each switching device in the single-phase current type five-level inverter circuit (1) are controlled after isolation driving.
2. Grid-connected harmonic suppression device based on single-phase current source type five-level inverter according to claim 1The manufacturing method is characterized in that: in step S4, the processing results in the capacitor voltage u c Fundamental component u of cb The specific method comprises the following steps: sampling capacitor voltage u c To the capacitor voltage u c Carrying out alpha beta-dq conversion and dq-alpha beta conversion treatment in sequence to obtain direct current u under dq coordinate system cd And u cq Then, the DC current u is applied cd And u cq Respectively processed by a low-pass filter in a low-pass filter processing circuit (7) of the capacitor feedback voltage to respectively obtain u cd And u cq Fundamental component u of cdb And u cqb And then carrying out dq-alpha beta inverse transformation to obtain a capacitor voltage u c Fundamental component u of cb 。
3. The grid-connected harmonic suppression method based on the single-phase current source type five-level inverter according to claim 1, characterized in that: the high-frequency harmonic component is equal to the capacitor voltage u c And the fundamental component u cb The difference between them.
CN202111542621.9A 2021-12-16 2021-12-16 Grid-connected harmonic suppression method based on single-phase current source type five-level inverter Pending CN114915195A (en)

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* Cited by examiner, † Cited by third party
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CN115642599A (en) * 2022-12-26 2023-01-24 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN116961018A (en) * 2023-09-18 2023-10-27 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115642599A (en) * 2022-12-26 2023-01-24 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN115642599B (en) * 2022-12-26 2023-03-31 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN116961018A (en) * 2023-09-18 2023-10-27 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof
CN116961018B (en) * 2023-09-18 2023-12-12 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof

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