CN113067492A - Parallel inverter switching frequency circulation restraining method based on carrier phase compensation - Google Patents

Parallel inverter switching frequency circulation restraining method based on carrier phase compensation Download PDF

Info

Publication number
CN113067492A
CN113067492A CN202110333040.8A CN202110333040A CN113067492A CN 113067492 A CN113067492 A CN 113067492A CN 202110333040 A CN202110333040 A CN 202110333040A CN 113067492 A CN113067492 A CN 113067492A
Authority
CN
China
Prior art keywords
inverter
compensated
phase
carrier
parallel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110333040.8A
Other languages
Chinese (zh)
Inventor
张继红
赵锐
熊伟
魏毅立
杨培宏
吴振奎
张新
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inner Mongolia University of Science and Technology
Original Assignee
Inner Mongolia University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Inner Mongolia University of Science and Technology filed Critical Inner Mongolia University of Science and Technology
Priority to CN202110333040.8A priority Critical patent/CN113067492A/en
Publication of CN113067492A publication Critical patent/CN113067492A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention discloses a parallel inverter switching frequency circulation restraining method based on carrier phase compensation, which comprises the following steps: (1) selecting an inverter to be compensated, and sampling three-phase output current of the inverter; (2) acquiring loop current data according to the three-phase current sampling data, extracting a direct current component in the loop current data, and judging the direction of the phase difference of the carrier of the inverter to be compensated according to the direct current component; (3) calculating a periodic phase difference and a phase shift period to be compensated based on the circulation data; (4) inputting the direction of the carrier phase difference obtained in the step (2) and the periodic phase difference and the phase shift period obtained in the step (3) into sine pulse width modulation, and correcting the carrier signal of the inverter to be compensated through the sine pulse width modulation.

Description

Parallel inverter switching frequency circulation restraining method based on carrier phase compensation
Technical Field
The invention belongs to the field of power electronics, relates to a micro-grid parallel inverter control technology, and particularly relates to a parallel inverter switching frequency circulating current restraining method based on carrier phase compensation.
Background
Wind power and photovoltaic energy supply have the advantages of environmental protection, inexhaustibility and the like, and the micro-grid provides directions for efficient utilization of new energy. Distributed micro sources and energy storage devices in the micro-grid are mostly connected to a common bus through inverters and are limited by the withstand voltage of power devices and the capacity of a single device, so that a multi-inverter parallel operation environment of the micro-grid is formed. Compared with the traditional control mode, the parallel scheme is more flexible and economical, and the user requirements are easily met.
Reliable parallel connection of inverters is a prerequisite for stable operation of the microgrid, however, circulation problems caused by differences of external characteristics of the inverters can cause current distortion, increase device loss and deteriorate system performance. The switching frequency circulation is inevitably introduced due to geographical factor limitation, failure of carrier synchronization technology, difference of each inverter carrier and the like.
The currently proposed suppression methods mostly aim at zero sequence and harmonic circulation, but rarely involve switching frequency circulation. Most of the existing methods for restraining the switching circulation are completed based on adjusting hardware parameters of equipment, but the ideal condition without deviation is difficult to realize in practical application, so that the inventor has great significance in providing the method for restraining the switching circulation from the perspective of a control method.
Disclosure of Invention
In order to solve the problem of switching frequency circulation caused by carrier asynchronism among the parallel inverters, the invention provides a parallel inverter switching frequency circulation restraining method based on carrier phase compensation.
The invention provides a parallel inverter switching frequency circulation restraining method based on carrier phase compensation, which is suitable for a micro-grid multi-inverter parallel system and comprises the following steps:
(1) selecting an inverter to be compensated, and sampling three-phase output current of the inverter;
(2) acquiring loop current data according to the three-phase current sampling data, extracting a direct current component in the loop current data, and judging the direction of the phase difference of the carrier of the inverter to be compensated according to the direct current component; when the direct current component is positive, the carrier phase is advanced; negative, the carrier phase lags;
(3) calculating the periodic phase difference to be compensated based on the circulation data
Figure BDA0002996211170000011
And period of phase shift
Figure BDA0002996211170000012
Wherein izRepresenting the magnitude of the circulating current, U, of the inverter to be compensateddcRepresenting the DC-side voltage, w, of the inverter to be compensatedcRepresenting the cut-off frequency of the inverter to be compensated, L representing the filter inductance of the inverter to be compensated, and T representing the period of the carrier signal;
(4) inputting the carrier phase difference direction obtained in the step (2) and the delta theta and the tau obtained in the step (3) into sine pulse width modulation, and correcting the carrier signal of the inverter to be compensated through the sine pulse width modulation; wherein, Δ θ is the phase value to be compensated of the inverter to be compensated, the carrier phase difference direction represents the correction direction, and the phase shift period is the time to be delayed of the inverter to be compensated.
Further, a low-pass filter is adopted to sample the three-phase output current of the inverter to be compensated.
Compared with the prior art, the invention has the following main advantages and beneficial effects:
according to the invention, according to the switching frequency sub-circulation characteristic in the switching period, the phase of the inverter carrier signal is subjected to delay compensation, so that the consistency of the parallel inverter carrier signals is realized, the inter-phase circulation of the parallel inverters is restrained, the switching frequency sub-circulation problem caused by the carrier difference among the parallel inverters is solved, and the system stability is improved. The method is suitable for the micro-grid multi-inverter parallel system.
Drawings
FIG. 1 is a diagram of a multiple inverter parallel configuration;
FIG. 2 is a topology block diagram of an inverter parallel system in an embodiment;
FIG. 3 is a schematic diagram of the switching frequency circulating current suppression of the present invention;
FIG. 4 is a block diagram of a carrier calculation module;
FIG. 5 is a simplified flow diagram of an embodiment;
fig. 6 is a schematic diagram of phase shifting of parallel carriers of inverters, wherein (a) is a schematic diagram of a triangular carrier signal, and (b) is an output voltage and a total output voltage of three inverters in a switching period.
In the figure, a 1-three-phase inverter bridge unit, a 2-LCL filtering unit and a 3-control unit are arranged.
Detailed Description
In order that those skilled in the art will better understand the present invention, the following detailed description of the technical solution of the present invention will be clearly and completely described, and it is obvious that the following description is only a detailed description, which does not limit the scope of the present invention.
Referring to fig. 1, a multi-inverter parallel scheme commonly used in a microgrid is shown, wherein the multi-inverter parallel scheme includes N inverters in parallel, and the multi-inverter parallel scheme is very likely to cause interaction among the inverters. In fig. 1, the inverters share a dc-side bus, and the ac-sides are directly connected in parallel. Each inverter mainly comprises a three-phase inverter bridge unit 1 and an LCL filtering unit 2.
The N inverters in fig. 1 have the same configuration, and the configuration will be described below with only the inverter 1 as a representative. The three-phase inverter bridge unit 1 comprises a switching tube S11、S31、S51Form an upper bridge arm of the inverter and a switch tube S41、S61、S21The inversion lower bridge arm is formed. The LCL filtering unit 2 comprises a bridge arm filtering inductor L11Network side filter inductor L12And a filter capacitor C11。R1Is impedance, Ra、Rb、RcRepresenting A, B, C three-phase loads, respectively.
Referring to fig. 2, a topology diagram of an inverter parallel system in an embodiment is shown. The inverter parallel system mainly comprises three inverters and a control unit which are connected in parallel, wherein the core of the control unit is a DSP control module and is used for carrying out digital control on the inverters. The driving module is connected between the DSP control module and the inverter and used for converting the instruction signal sent by the DSP control module and applying the instruction signal to the inverter to generate a signal for switching on or off each switching tube of the inverter. The carrier phase shift module is connected between the DSP control module and the driving module and is used for applying a carrier phase difference signal to a carrier generator of the inverter.
Referring to fig. 3, a schematic diagram of the switching-frequency circulating current suppression of the present invention is shown, and the control strategy of the present invention is described in conjunction with the schematic diagram. First, a conventional control method of the parallel inverter system is: three-phase voltage U input to each invertera、Ub、UcThrough a phase-locked loop PLL and then connected with an output voltage signal U of the inverterdcAnd a voltage reference signal UrefThe two are controlled by a PI outer ring and a dead beat inner ring, and finally are transmitted to a Sinusoidal Pulse Width Modulation (SPWM). Meanwhile, three-phase current sampling is carried out on the inverter, carrier calculation is carried out on the basis of current sampling data by a carrier calculation module to obtain a phase shift period tau, and the phase shift period tau is also transmitted to the sinusoidal pulse width modulation SPWM. The sine pulse width modulation obtains an inverter modulation signal based on a phase shift period tau, and carries out compensation based on a carrier phase. The calculation principle of the carrier calculation module is shown in fig. 4, and the calculation principle will be described in detail later with reference to the method flow.
FIG. 5 is a schematic flow diagram of the process of the present invention, and a specific embodiment of the process of the present invention will be provided in conjunction with FIG. 5.
First, the technical principle of the implementation of the present invention will be described by taking the inverter parallel system shown in fig. 2 as an example. Defining the switching function S of the parallel configuration of the inverters in FIG. 2jkThe following are:
Figure BDA0002996211170000031
in the formula (1), j is the inverter number, and j can be 1, 2 and 3 in sequence; k represents the three phases of the inverter, i.e., the A, B, C phases. When S isjkWhen the value is 0, the upper inverter arm switch of the inverter j is disconnected, and the lower inverter arm switch is closed; when S isjkWhen 1, then representsAnd an upper inverter arm switch of the inverter j is closed, and a lower inverter arm switch is opened.
And assuming that the hardware parameter characteristics of the three parallel inverters are consistent, and only the conduction states of the switching tubes are different. Let uc1、uc2、uc3Respectively representing the triangular carrier signals, u, of three inverters in parallelc1、uc2、uc3The amplitudes are the same, but the phases are sequentially different by 120 degrees, and a triangular carrier signal uc1、uc2、uc3As shown in fig. 6 (a).
Referring to fig. 6, which shows a schematic diagram of the phase shift of the parallel carrier of the inverter, diagram (a) is a triangular carrier signal uc1、uc2、uc3In which (b) shows the output voltages u of three inverters in a switching cycleg1、ug2、ug3And output total voltage ug. Based on the schematic diagram, the carrier signal u of three parallel inverters can be knownc1、uc2、uc3Mutually phase-shifted by an angle θ:
Figure BDA0002996211170000032
i.e. the triangular carrier signal uc1、uc2、uc3Phase difference in sequence
Figure BDA0002996211170000033
The voltage difference fluctuates once up and down in the switching period to generate switching frequency circulation.
Based on the analysis, the phase of the parallel inverter carrier signal has a linear relationship with the system switch loop current, that is, the loop current size is related to the period length of carrier phase asynchronization.
The following will provide a process for carrying out the present invention.
S1, selecting the inverter to be compensated, and sampling the three-phase output current of the inverter to be compensated by using the low-pass filter.
S2, obtaining circulation data according to the three-phase current sampling data, extracting direct current components in the circulation data, judging the direction of carrier phase difference, and when the direct current components are positive, leading the carrier phase of the inverter to be compensated; and if the voltage is negative, the carrier phase of the inverter to be compensated lags.
S3 calculates the period phase difference Δ θ and the phase shift period τ to be compensated based on the carrier calculation module.
Obtaining the magnitude of the circulating current from the three-phase current sampling data collected in the step S1, and recording the magnitude as izBased on the size of the circulation izThe periodic phase difference delta theta and the phase shift period tau between the carrier signals are calculated.
Magnitude of inverter circulating current izIs calculated as:
iz＝ija+ijb+ijc (3)
in the formula (3), ijaRepresenting phase a current, i, of the jth inverterjbRepresenting phase b current, i, of the jth inverterjcRepresenting the c-phase current of the jth inverter. In this embodiment, the jth inverter is referred to as a to-be-compensated inverter.
The periodic phase difference Δ θ between the inverter carrier signals is:
Figure BDA0002996211170000041
in the formula (4), UdcRepresenting the DC-side voltage, w, of the inverter to be compensatedcThe cutoff frequency of the inverter to be compensated is represented, and the filter inductance of the inverter to be compensated is represented by L.
The phase shift period τ is then:
Figure BDA0002996211170000042
in the formula (5), T represents a carrier signal period.
S4: and correcting carrier signals among the inversion modules, and respectively obtaining modulation signals of the parallel inverters through Sinusoidal Pulse Width Modulation (SPWM) so as to complete phase compensation.
And inputting the result obtained in the steps S1-S3 into a Sinusoidal Pulse Width Modulation (SPWM), and correcting and adjusting the carrier signal of the inverter to be compensated through the Sinusoidal Pulse Width Modulation (SPWM). The period phase difference is the phase value compensated by the inverter to be compensated, and the phase shift period is the time delay required by the inverter to be compensated.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed in all aspects and as broadly as possible, and all changes, equivalents and modifications that fall within the true spirit and scope of the invention are therefore intended to be embraced therein.

Claims (2)

1. A parallel inverter switching frequency circulation restraining method based on carrier phase compensation is suitable for a micro-grid multi-inverter parallel system and is characterized by comprising the following steps:
(1) selecting an inverter to be compensated, and sampling three-phase output current of the inverter;
(2) acquiring loop current data according to the three-phase current sampling data, extracting a direct current component in the loop current data, and judging the direction of the phase difference of the carrier of the inverter to be compensated according to the direct current component; when the direct current component is positive, the carrier phase is advanced; negative, the carrier phase lags;
(3) calculating the periodic phase difference to be compensated based on the circulation data
Figure FDA0002996211160000011
And period of phase shift
Figure FDA0002996211160000012
Wherein izRepresenting the magnitude of the circulating current, U, of the inverter to be compensateddcRepresenting the DC-side voltage, w, of the inverter to be compensatedcRepresenting the cut-off frequency of the inverter to be compensated, L representing the filter inductance of the inverter to be compensated, and T representing the period of the carrier signal;
(4) inputting the carrier phase difference direction obtained in the step (2) and the delta theta and the tau obtained in the step (3) into sine pulse width modulation, and correcting the carrier signal of the inverter to be compensated through the sine pulse width modulation; wherein, Δ θ is the phase value to be compensated of the inverter to be compensated, the carrier phase difference direction represents the correction direction, and the phase shift period is the time to be delayed of the inverter to be compensated.
2. The method for restraining the switching frequency secondary circulating current of the parallel inverter based on the carrier phase compensation as claimed in claim 1, is characterized in that:
and sampling the three-phase output current of the inverter to be compensated by adopting a low-pass filter.
CN202110333040.8A 2021-03-29 2021-03-29 Parallel inverter switching frequency circulation restraining method based on carrier phase compensation Pending CN113067492A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110333040.8A CN113067492A (en) 2021-03-29 2021-03-29 Parallel inverter switching frequency circulation restraining method based on carrier phase compensation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110333040.8A CN113067492A (en) 2021-03-29 2021-03-29 Parallel inverter switching frequency circulation restraining method based on carrier phase compensation

Publications (1)

Publication Number Publication Date
CN113067492A true CN113067492A (en) 2021-07-02

Family

ID=76564209

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110333040.8A Pending CN113067492A (en) 2021-03-29 2021-03-29 Parallel inverter switching frequency circulation restraining method based on carrier phase compensation

Country Status (1)

Country Link
CN (1) CN113067492A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114257074A (en) * 2021-12-15 2022-03-29 中车长春轨道客车股份有限公司 Inverter parallel switch circulating current suppression algorithm based on carrier phase synchronization

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102231608A (en) * 2011-07-04 2011-11-02 浙江大学 DC (direct current) loop-current suspension device for inverter parallel system
CN106505900A (en) * 2016-12-26 2017-03-15 哈尔滨工业大学 A kind of arcless breaking inverter loop current suppressing method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102231608A (en) * 2011-07-04 2011-11-02 浙江大学 DC (direct current) loop-current suspension device for inverter parallel system
CN106505900A (en) * 2016-12-26 2017-03-15 哈尔滨工业大学 A kind of arcless breaking inverter loop current suppressing method

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
刘建宝等: "基于载波相位调节的SPWM逆变器并联***环流电流抑制方法", 《海军工程大学学报》 *
阳敏等: "多逆变器并联***环流分析及抑制方法", 《电力***及其自动化学报》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114257074A (en) * 2021-12-15 2022-03-29 中车长春轨道客车股份有限公司 Inverter parallel switch circulating current suppression algorithm based on carrier phase synchronization
CN114257074B (en) * 2021-12-15 2024-03-08 中车长春轨道客车股份有限公司 Inverter parallel switch circulation suppression algorithm based on carrier phase synchronization

Similar Documents

Publication Publication Date Title
CN102856916B (en) Reactive power control method and circuit of single-phase photovoltaic inverter
CN105897013B (en) A kind of virtual inertia control method of two-way AC/DC converters
CN107196491B (en) A kind of double buck gird-connected inverter half period current distortion inhibition system and method
CN109639160B (en) Novel unidirectional three-phase three-level rectifier based on soft switching technology
CN105958856A (en) Novel hybrid MMC topology with capabilities of direct current fault removing and partial automatic voltage sharing
CN103647470B (en) A kind of three-phase NPC photovoltaic combining inverter based on Repetitive controller
CN111953223B (en) Neutral point voltage balancing method for three-phase four-wire system three-level converter
CN104767365B (en) T-shaped three level DC/AC converters DC voltage ripple compensation system and method
CN103812375A (en) System and method for controlling off-network operation for three-phase four-leg inverter circuit
CN108767873B (en) High-reliability damping remodeling method for large new energy power station
CN102291030A (en) Method for controlling balance of three-level photovoltaic grid-connected inverter direct current voltage
Li et al. Predictive zero-sequence current control of multiple paralleled power converters
EP3723264B1 (en) Single-phase five-level converter control method and device
CN113629763B (en) Current control method and system for medium-voltage direct-hanging energy storage converter under non-ideal power grid
CN105978020B (en) The optimization modulator approach and system of non-isolated alternating current bypass type single-phase grid-connected inverter
CN113067492A (en) Parallel inverter switching frequency circulation restraining method based on carrier phase compensation
CN105006841A (en) Three-phase grid-connected inverter seamless grid-connected controller and control method thereof
CN109830995B (en) Island control strategy based on energy router
CN117039976A (en) CLLC bidirectional resonant converter cascading grid-connected inverter and inhibition method thereof
CN116565944A (en) Synchronous frequency adaptive resonance-based negative sequence voltage compensation method for grid-structured converter
Pan et al. Fractional-order sliding mode control strategy for quasi-Z source photovoltaic grid-connected inverter
CN107612398A (en) A kind of five level NPC type inverter Passive Shape Control system and methods
CN114069633A (en) Hybrid intelligent distribution transformer containing high-frequency isolated back-to-back converter
Fu et al. High-reliability three-phase dual-buck grid-connected inverter without shoot-through problem
CN110912130A (en) Circuit structure of double-alternating-current bus grid-connected converter and harmonic compensation method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20210702