CN105610344A - Multiphase photovoltaic inverter and control method thereof - Google Patents

Multiphase photovoltaic inverter and control method thereof Download PDF

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Publication number
CN105610344A
CN105610344A CN201610169902.7A CN201610169902A CN105610344A CN 105610344 A CN105610344 A CN 105610344A CN 201610169902 A CN201610169902 A CN 201610169902A CN 105610344 A CN105610344 A CN 105610344A
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China
Prior art keywords
converter
photovoltaic
heterogeneous
voltage
module
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Chinese (zh)
Inventor
王振中
刘志刚
胡益
闫飞朝
孙东海
郭剑
洪熊祥
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China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd
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China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd
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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
    • H02M7/53—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
    • H02M7/53871—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 with automatic control of output voltage or current
    • 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
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M7/53871—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 with automatic control of output voltage or current
    • H02M7/53875—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 with automatic control of output voltage or current with analogue control of three-phase output
    • H02M7/53876—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 with automatic control of output voltage or current with analogue control of three-phase output based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H02M1/325—Means for protecting converters other than automatic disconnection with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
    • 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

Abstract

The invention discloses a multiphase photovoltaic inverter and a control method thereof. The multiphase photovoltaic inverter comprises a direct-current circuit breaker, a DC/DC converter, a five-phase inverter bridge, a multi-phase filter and an alternating-current circuit breaker, wherein the output end of the direct-current circuit breaker is electrically connected with the input end of the DC/DC converter, the output end of the DC/DC converter is electrically connected with the input end of the five-phase inverter bridge, the output end of the five-phase inverter bridge is electrically connected with the multi-phase filter, and the multi-phase filter is electrically connected with the alternating-current circuit breaker. The multiphase photovoltaic inverter has the advantages of large linear modulation range, high utilization rate of alternating-current power and low harmonic components in output voltage and current.

Description

Heterogeneous photovoltaic DC-to-AC converter and control method thereof
Technical field
The present invention relates to field of photovoltaic power generation, be specifically related to a kind of heterogeneous photovoltaic DC-to-AC converter and control method thereof.
Background technology
Solar energy has the advantages such as safety, clean and resource generality, can become that to substitute fossil energy mainRegenerative resource. Solar energy power generating is in its developmental research, market development and industrialized manufacture technologyAlready as the focus of global various countries keen competition. Due to the large-scale development of photovoltaic industry, therefore three-phase lightThe defects such as volt inverter capacity is little, conversion efficiency is low have become restriction photovoltaic plant to intelligent, modularizationThe bottleneck of development. Meanwhile, due to the extensive use of power electronic devices, that electric power system is no longer subject to is traditionalThe restriction of the three phase supply number of phases, multiphase system (number of phases is more than the system of three-phase) gets the attention. ManyPhase system has improved the power output of whole system, is particularly suitable for application and electric locomotive traction, marine vessel powerThe fields such as propelling, Aero-Space.
Therefore, existing three-phase photovoltaic DC-to-AC converter has following defect:
The first, when direct current is converted to industrial-frequency alternating current by inverter, harmonic content is high, and conversion efficiency is low;
The second, the capacity of inverter is little, is unsuitable for extensive, jumbo photovoltaic array.
Summary of the invention
The object of this invention is to provide a kind of heterogeneous photovoltaic DC-to-AC converter and control method thereof, thereby solve above-mentioned existingThere is the problem existing in technology.
In order to address the above problem, according to an aspect of the present invention, provide a kind of heterogeneous photovoltaic DC-to-AC converter,Described heterogeneous photovoltaic DC-to-AC converter comprises dc circuit breaker, DC/DC converter, multi-phase inverter bridge, multiphase filteringDevice and AC circuit breaker, wherein, the output of described dc circuit breaker and described DC/DC converter defeatedEnter end electrical connection, the output of described DC/DC converter is electrically connected with the input of described multi-phase inverter bridge,The output of described multi-phase inverter bridge is electrically connected with described multiphase filter, and described multiphase filter and instituteState AC circuit breaker electrical connection.
Preferably, described multi-phase inverter bridge is five phase inverter bridge, and described multiphase filter is five phase filters,And described heterogeneous photovoltaic DC-to-AC converter also comprises SPWM module, PMU module, MPPT module and calculates mouldPiece, wherein said SPWM module connects by control line and described five phase inversion bridgings, and described PMU module is logicalCross holding wire and be connected with described SPWM module, described MPPT module connects by holding wire and described PMU moduleConnect, and described computing module is electrically connected with described MPPT module;
When operation, described MPPT module is come real by controlling the break-make of IGBT pipe in DC/DC moduleThe tracking of existing described heterogeneous photovoltaic DC-to-AC converter maximum power point, described PMU module sends instruction to describedSPWM module, described SPWM module passes through to control the IGBT pipe break-make of described five phase inverter bridge, therebyObtain the voltage signal of expecting.
Preferably, described heterogeneous photovoltaic DC-to-AC converter has 1/4 working method and 2/3 working method; Wherein
Described 1/4 working method refers at a time, and the upper brachium pontis of described five phase inverter bridge has one to be conducted,Lower brachium pontis has four to be conducted, or the upper brachium pontis of described five phase inverter bridge has four to be conducted, and lower brachium pontis has one to lead mutuallyLogical; And
Described 2/3 working method refers at a time, and the upper brachium pontis of described five phase inverter bridge has two to be conducted,Lower brachium pontis has three to be conducted, or the upper brachium pontis of described five phase inverter bridge has three to be conducted, and lower brachium pontis has two-phase to leadLogical.
Preferably, in described 1/4 working method and 2/3 working method, upper brachium pontis conducting mutually adjacent,And lower brachium pontis conducting is mutually adjacent.
Preferably, described PMU module and SPWM module are electrically connected with power supply.
Preferably, described SPWM module is provided with the circuit of carrying out following process:
(1) set up the switching equation of heterogeneous photovoltaic DC-to-AC converter: S=[Sa，Sb，Sc，Sd，St], wherein,Sk=1 represents that on photovoltaic DC-to-AC converter a phase brachium pontis, switch conduction, lower switch turn-off, Sk=0 represents upper switchShutoff, lower switch conduction, wherein k=a, b, c, d, or e;
(2) set up the pole tension equation of heterogeneous photovoltaic DC-to-AC converter: uk0＝SkUd-Ud/2；
(3) set up the voltage vector equation of heterogeneous photovoltaic DC-to-AC converter:
(4) obtain 32 voltage vectors of heterogeneous photovoltaic DC-to-AC converter, these 32 voltage vectors comprise greatlyVector ULi, i be >=1 and≤10 integer, middle vector UMj, j be >=1 and≤10 integer, little arrowAmount USn, n be >=1 and≤10 integer, and two zero vector U0, wherein these 32 voltage vectorsBe scattered in 10 sectors, each sector comprises two large vectors, two middle vectors, two small vectorsAn and zero vector;
(5) synthesized reference voltage Uref: establish reference voltage UrefBe positioned at k sector, select UL(k+1)、UMk、UM(k+2)And a zero vector carrys out synthesized reference voltage Uref；
(6) obtain voltage UL(k+1)、UMk、UM(k+2)And U0Action time.
Preferably, described heterogeneous photovoltaic DC-to-AC converter also comprises direct current EMC wave filter, described direct current EMC filteringDevice is arranged between described dc circuit breaker and described DC/DC converter, wherein said direct current EMC wave filterInput be electrically connected with the output of described dc circuit breaker, and the output of described direct current EMC wave filterEnd is electrically connected with the input of described DC/DC converter.
Preferably, described heterogeneous photovoltaic DC-to-AC converter also comprises interchange EMC wave filter, described interchange EMC filteringDevice is arranged between described multiphase filter and described AC circuit breaker, wherein said interchange EMC wave filterInput is electrically connected with the output of described multiphase filter, and the output of described interchange EMC wave filterBe electrically connected with the input of described AC circuit breaker.
According to a further aspect in the invention, also provide a kind of control method of above-mentioned heterogeneous photovoltaic DC-to-AC converter,Said method comprising the steps of:
(1) break-make of controlling the IGBT pipe in described DC/DC module realizes described heterogeneous photovoltaicThe tracking of inverter maximum power point;
(2) set up the switching equation of heterogeneous photovoltaic DC-to-AC converter: S=[Sa，Sb，Sc，Sd，Se], wherein,Sk=1 represents switch conduction on photovoltaic DC-to-AC converter a phase brachium pontis, and lower switch turn-offs; Sa=0 represents upper switchTurn-off lower switch conduction, k=a, b, c, d or e;
(3) set up the pole tension equation of heterogeneous photovoltaic DC-to-AC converter: uk0＝SkUd-Ud/2；
(4) set up the voltage vector equation of heterogeneous photovoltaic DC-to-AC converter:
(5) obtain 32 voltage vectors of heterogeneous photovoltaic DC-to-AC converter, these 32 voltage vectors comprise greatlyVector ULi, i be >=1 and≤10 integer, middle vector UMj, j be >=1 and≤10 integer, little arrowAmount USn, n be >=1 and≤10 integer, and two zero vector U0, wherein these 32 voltage vectorsBe scattered in 10 sectors, each sector comprises two large vectors, two middle vectors, two small vectorsAn and zero vector;
(6) synthesized reference voltage Uref: establish reference voltage UrefBe positioned at k sector, select UL(k+1)、UMk、UM(k+2)An and zero vector U0Carry out synthesized reference voltage Uref；
(7) obtain voltage UL(k+1)、UMk、UM(k+2)And U0Action time.
Preferably, obtain voltage U by following stepsL(k+1)、UMk、UM(k+2)And U0Action time:
Be located at a switch periods TsThe action time of interior k vector is Tk, set up in k sector and vowAmount equilibrium equation:
T s U r e f = T L ( k + 1 ) U L ( k + 1 ) + T M k U M K + T M ( k + 2 ) U M ( K + 2 ) T s = T L ( k + 1 ) + T M k + T M ( k + 2 ) + T 0
Thereby obtain TL(k+1)、T(M+2)k、TMkAnd T0。
Preferably, voltage UL(k+1)、UMk、UM(k+2)And U0Sequence of operation be: UMk→UL(k+1)→UM(k+2)→U0→UM(k+2)→UL(k+1)→UMk。
Preferably, as described UrefWhile being positioned at first sector, voltage U M1、UL2、UM3And U0Effect suitableOrder is UM1(10000)→UL2(11000)→UM3(01000)→U0(00000)→UM3(01000)→UL2(11000)→UM1(10000)。
Heterogeneous photovoltaic DC-to-AC converter of the present invention possesses following advantage:
(1) heterogeneous control system is larger than the modulation index of traditional three-phase system, therefore heterogeneous photovoltaic DC-to-AC converterLinear modulation scope larger, dc source utilization rate is higher;
(2) harmonic component in heterogeneous photovoltaic inverter output voltage and electric current reduces;
(3) in heterogeneous one mutually or several while breaking down mutually, by suitable control, photovoltaic DC-to-AC converterStill can be by energetic start up and operation, system reliability is high;
(4) improve to greatest extent transformation efficiency and the grid connection capacity of photovoltaic DC-to-AC converter.
Brief description of the drawings
Fig. 1 is the topology diagram of the heterogeneous photovoltaic DC-to-AC converter of the present invention;
Fig. 2 is another topology diagram of the heterogeneous photovoltaic DC-to-AC converter of the present invention;
Fig. 3 is the space voltage vector figure of the heterogeneous photovoltaic DC-to-AC converter of the present invention, and wherein small voltage vector is not shown;And
Fig. 4 is the PWM waveform of the first sector of obtaining by heterogeneous photovoltaic inverter control method of the present inventionFigure.
Detailed description of the invention
Below with reference to accompanying drawing, preferred embodiment of the present invention is elaborated, so that clearer understanding originallyThe objects, features and advantages of invention. It should be understood that embodiment shown in the drawings is not to model of the present inventionThe restriction of enclosing, and just for the connotation of technical solution of the present invention is described.
Term explanation
Photovoltaic DC-to-AC converter: inverter is by power electronic devices (MOSFET, IGBT etc.) contact resistance electricityHold, with the break-make of the mode control device of pulse width modulation, the direct current that header box transmission is come is transformed intoAlternating current completes the MPPT maximum power point tracking (MPPT) of photovoltaic module simultaneously, ensures Based Intelligent Control and anti-lonelyIsland effect etc.
DC/DC converter: realization is boosted to photovoltaic array completes photovoltaic array output maximum work simultaneouslyThe tracking (MPPT) of rate.
Inverter bridge: adopt full bridge structure, convert direct current to industrial-frequency alternating current.
Fig. 1 is the topology diagram of heterogeneous photovoltaic DC-to-AC converter of the present invention. As shown in Figure 1, of the present invention manyPhase photovoltaic DC-to-AC converter generally include dc circuit breaker 10A, DC/DC converter 20, multi-phase inverter bridge 30A,Multiphase filter 40A and AC circuit breaker 50A, wherein, the output of dc circuit breaker 10A and DC/DCThe input electrical connection of converter 20, the output of DC/DC converter 10A and multi-phase inverter bridge 30A's is defeatedEnter end electrical connection, the output of multi-phase inverter bridge 30A is electrically connected with multiphase filter 40A, and heterogeneous filterRipple device 40A is electrically connected with AC circuit breaker 50A, and wherein DC/DC converter 20 is for realizing photovoltaic battle arrayThe raising of row output voltage.
In one embodiment of this invention, heterogeneous photovoltaic DC-to-AC converter also comprises SPWM module 60 and PMU module70, wherein SPWM module 60 is connected with multi-phase inverter bridge 30A by control line, and PMU module 70 is by letterNumber line is connected with SPWM module 60, and when operation, PMU module 70 sends instruction to SPWM module 60,SPWM module 60 passes through to control the IGBT pipe break-make of multi-phase inverter bridge 30A, thereby obtains the electricity of expectingPress signal.
In another embodiment of the present invention, heterogeneous photovoltaic DC-to-AC converter 100 also comprises direct current EMC wave filter,Direct current EMC wave filter is arranged between dc circuit breaker 10 and DC/DC converter, direct current EMC wave filterInput be electrically connected with the output of dc circuit breaker 10, output and the DC/DC of direct current EMC wave filterThe input electrical connection of converter, direct current EMC wave filter is realized the effect of filtering electromagnetism harmonic wave.
In another embodiment of the present invention, heterogeneous photovoltaic DC-to-AC converter 100 also comprises interchange EMC wave filter,Exchange EMC wave filter and be arranged between five phase filters 30 and AC circuit breaker 40, exchange EMC wave filterInput be electrically connected with the output of multiphase filter 30, the output that exchanges EMC wave filter with exchangeThe input electrical connection of breaker 30, interchange EMC wave filter is realized the effect of filtering electromagnetism harmonic wave.
The number of phases of heterogeneous photovoltaic DC-to-AC converter of the present invention can be any phase that is greater than three-phase, such as 4 phases, 5Phase, 6 phases, 7 equate. For for simplicity, below describe as an example of five phase photovoltaic DC-to-AC converters example.
Fig. 2 is the topology diagram of five phase photovoltaic DC-to-AC converters of the present invention. As shown in Figure 2, five phase photovoltaics are contraryBecome device 100 and comprise dc circuit breaker 10, DC/DC converter 20, five phase inverter bridge 30, five phase filters40 and AC circuit breaker 50, wherein, the output of dc circuit breaker 10 and DC/DC converter 20Input electrical connection, the output of DC/DC converter 20 is electrically connected with the input of five phase inverter bridge 30,The output of five phase inverter bridge 30 is electrically connected with five phase filters 40, and five phase filters 40 with exchangeBreaker 50 is electrically connected, and wherein DC/DC converter is used for realizing the raising to photovoltaic array output voltage,Complete the tracking (MPPT) of maximum power point.
20 of five phase inverter bridge comprise 10 IGBT switching tube: S1～S10, five phase filters 30 adopt RLCMode filter, R represents the internal resistance of wave filter and the voltage that caused by the upper and lower interlocking of every phase brachium pontis dead band damagesLose, L represents grid-connected wave filter.
As shown in Figure 2, five phase photovoltaic DC-to-AC converters 100 of the present invention also comprise SPWM module 60, PMU mouldPiece 70, MPPT module 80 and computing module 90, wherein SPWM module 60 by control line 61 respectively10 IGBT switching tube S with five phase inverter bridge 201～S10Connect, thereby by SPWM module 60 energyEnough control IGBT pipe S1～S10Conducting and disconnection, PMU module 70 is by holding wire 71 and SPWM module60 connect, thereby can send instruction to SPWM module 60.
SPWM module 60 is all connected with power supply by wire respectively with PMU module 70, and arrow 62,63Represent respectively signal wave and carrier wave, it is scaled as modulation that signal wave refers to the waveform that hope is obtainedSignal, this modulation signal is sinusoidal wave in the present invention, carrier wave refers to the signal of accepting modulation.
MPPT module 80 is connected with the IGBT pipe of DC/DC converter by control line 81 on the one hand, anotherAspect is electrically connected with PMU module by holding wire 82, in addition, MPPT module 80 also with computing module 90Signal communication.
In Fig. 2, UdcBe the capacitance voltage of DC/DC module 20, dU is voltage variety, Udc+dUIt is the voltage after changing.
When operation, UdcThe value of+dU is delivered to MPPT module 80 by holding wire, and MPPT module 80 is adjustedThe dutycycle of whole IGBT pipe completes the tracking of power points, wherein, before the power after adjusting and adjustmentPower difference DELTA P > 0 o'clock, next step voltage adjustment is still for increasing step-length adjustment, and when the power after adjustmentWith adjust before power difference DELTA P < 0 time, next step voltage adjustment is still for subtracting step-length adjustment. Increase stepLong adjust to refer to power is tuned up, subtract step-length adjustment and refer to power is turned down.
The present invention passes through the MPPT maximum power point tracking of MPPT module, thereby realizes solar cell in photovoltaic systemAll the time Maximum Power Output.
When MPPT module 80 realizes MPPT maximum power point tracking, SPWM module 60 and PMU module70 realize the control of five phase photovoltaic DC-to-AC converter output voltages. Be specially and reach SPWM module when carrier signal60 o'clock, SPWM module 60 reached PMU module 70 by holding wire by this carrier signal, PMU module 70Send instruction to SPWM module 60, SPWM module 60 is carried out and is calculated comparing function, and by controlling line traffic control10 IGBT pipe pipe S of multi-phase inverter bridge 20 processed1～S10Break-make, thereby obtain expect voltage signal.
Heterogeneous photovoltaic inverter topology of the present invention is simple, has advantages of the amount of capacity of not being subject to restriction.But control mode is relative complex also, below specifically introduce Multi-phase light of the present invention as an example of five phase photovoltaic DC-to-AC converters exampleThe control method of volt inverter. This control method realizes by SPWM module and PMU module.
If the switch function of polyphase inverter is
S＝[Sa，Sb,…，Sn](1)
If Sa=1, represent switch conduction on photovoltaic DC-to-AC converter a phase brachium pontis, lower switch turn-offs, outputThe voltage (pole tension) of point to power center's point O is Ud/ 2; If Sa=0, switch on a phase brachium pontisTurn-off, lower switch conduction, output stage voltage is-Ud/ 2, other each switch functions are identical with it.
Now, polyphase inverter output stage voltage is expressed as with switch function
uk0＝SkUd-Ud/2(2)
Heterogeneous photovoltaic DC-to-AC converter output line voltage can be expressed as
u a b u b c . . . u n 1 = U d 1 - 1 ... 0 0 1 - 1 ... 0 0 ... - 1 - 1 0 0 1 S a S b . . . S n - - - ( 3 )
Heterogeneous photovoltaic DC-to-AC converter output phase voltage can be expressed as
u a N u b N . . . u n N = U d n ( R - 1 ) - 1 ... - 1 - 1 ( R - 1 ) - 1 ... - 1 - 1 ... - 1 - 1 - 1 - 1 ( n - 1 ) S a S b . . . S n - - - ( 4 )
Therefore, space vector of voltage equation is
U k = 2 n &lsqb; u a N + e j 2 &pi; n u b N + e j 4 &pi; n u c N + ... + e j 2 ( n - 1 ) &pi; n u n N &rsqb; - - - ( 5 )
Formula (4) is brought into formula (5) and obtains,
U k = 2 n U d &lsqb; S a + e j 2 &pi; n S b + e j 4 &pi; n S c + ... + e j 2 ( n - 1 ) &pi; R S n &rsqb; - - - ( 6 )
According to above-mentioned definition, can obtain altogether 2 through calculatingnIndividual voltage vector. Wherein, these vector foundationsDifferent amplitudes are divided into different groups, also comprise in addition 0 vector. Effective vector correspondence of different amplitudes five phasesThe different operating state of photovoltaic DC-to-AC converter. I.e. 1/4 working method, 2/3 working method and pseudo-2/3 working method.So-called 2/3 working method refers at a time, and on photovoltaic DC-to-AC converter, brachium pontis has two to be conducted, and lower brachium pontis hasOtherwise three be conducted or, and upper brachium pontis (or lower brachium pontis) conducting is mutually adjacent, can make synthetic voltageVector maximum. 1/4 working method is similar with it. Pseudo-2/3 working method is by brachium pontis (or lower brachium pontis) thereonThe three-phase of conducting is simultaneously not all adjacent, and centre exists the phase of not conducting, for preventing from causing the excitation between phase and phaseDisturb, therefore should avoid using.
The present invention adopts 2/3 working method and 1/4 working method Comprehensive Control, thereby makes the waveform of outputComparatively steady. Under this control method, adopt a large vector, zero vector pair of two middle vectorsReference voltage in sector synthesizes.
Describe as an example of first sector example below, select UM1(10000)、UL2(11000)、UM3And U (01000)0(00000) vector is to reference voltage UrefSynthesize. In the sequence of operation of the first sectorFor UM1(10000)→UL2(11000)→UM3(01000)→U0(00000)→UM3(01000)→UL2(11000)→UM1(10000)。
Be located at a switch periods TsThe action time of interior k vector is Tk, vector in each sectorEquilibrium equation is:
T s U r e f = T L ( k + 1 ) U L ( k + 1 ) + T M k U M K + T M ( k + 2 ) U M ( K + 2 ) T s = T L ( k + 1 ) + T M k + T M ( k + 2 ) + T 0 - - - ( 1 )
According to formula (1), can obtain time variable TL(k+1)、T(M+2)k、TMkAnd T0Value, wherein, the partyPWM waveform under formula is shown in Fig. 4.
Known by above analysis, the control method of the heterogeneous photovoltaic DC-to-AC converter of the present invention of the present invention is mainly wrappedDraw together following steps:
(1) set up the switching equation of heterogeneous photovoltaic DC-to-AC converter: S=[Sa，Sb，Sc，Sd，Se], wherein,Sk=1 represents switch conduction on photovoltaic DC-to-AC converter a phase brachium pontis, and lower switch turn-offs; Sa=0 represents upper switchTurn-off lower switch conduction, k=a, b, c, d or e;
(2) set up the pole tension equation of heterogeneous photovoltaic DC-to-AC converter: uk0＝SkUd-Ud/2；
(3) set up the voltage vector equation of heterogeneous photovoltaic DC-to-AC converter:
(4) obtain 32 voltage vectors of heterogeneous photovoltaic DC-to-AC converter.
Fig. 3 is the PWM waveform of the first sector of obtaining of heterogeneous photovoltaic inverter control method according to the present inventionFigure. As shown in Figure 3, these 32 voltage vectors comprise large vector ULi, i be >=1 and≤10 integer,Middle vector UMj, j be >=1 and≤10 integer, small vector USn(not shown), n be >=1 and≤10Integer, and two zero vector U0, wherein these 32 voltage vectors are scattered in 10 sectors, everySector comprises two large vectors, two middle vectors, two small vector (not shown) and oneZero vector;
(5) synthesized reference voltage Uref: establish reference voltage UrefBe positioned at k sector, select UL(k+1)、UMk、UM(k+2)An and zero vector U0Carry out synthesized reference voltage Uref；
(6) obtain voltage UL(k+1)、UMk、UM(k+2)And U0Action time:
Be located at a switch periods TsThe action time of interior k vector is Tk, set up in k sector and vowAmount equilibrium equation:
T s U r e f = T L ( k + 1 ) U L ( k + 1 ) + T M k U M K + T M ( k + 2 ) U M ( K + 2 ) T s = T L ( k + 1 ) + T M k + T M ( k + 2 ) + T 0
Thereby obtain TL(k+1)、T(M+2)k、TMkAnd T0。
Heterogeneous photovoltaic DC-to-AC converter of the present invention has the following advantages:
(1) heterogeneous control system is larger than the modulation index of traditional three-phase system, therefore heterogeneous photovoltaic DC-to-AC converterLinear modulation scope larger, dc source utilization rate is higher;
(2) harmonic component in heterogeneous photovoltaic inverter output voltage and electric current reduces;
(3) in heterogeneous one mutually or several while breaking down mutually, by suitable control, photovoltaic DC-to-AC converterStill can be by energetic start up and operation, system reliability is high;
(4) transformation efficiency and the grid connection capacity of photovoltaic DC-to-AC converter have been improved to greatest extent, simultaneously output waveShape is comparatively steady.
Below describe preferred embodiment of the present invention in detail, but it will be appreciated that, read thisAfter bright above-mentioned instruction content, those skilled in the art can make various changes or modifications the present invention.These equivalent form of values fall within the application's appended claims limited range equally.

Claims (10)

1. a heterogeneous photovoltaic DC-to-AC converter, is characterized in that, described heterogeneous photovoltaic DC-to-AC converter comprises that direct current is disconnectedRoad device, DC/DC converter, multi-phase inverter bridge, multiphase filter and AC circuit breaker, wherein, described inThe output of dc circuit breaker is electrically connected with the input of described DC/DC converter, described DC/DC converterOutput be electrically connected with the input of described multi-phase inverter bridge, the output of described multi-phase inverter bridge with described inMultiphase filter electrical connection, and described multiphase filter is electrically connected with described AC circuit breaker.
2. heterogeneous photovoltaic DC-to-AC converter according to claim 1, is characterized in that, described multi-phase inverterBridge is five phase inverter bridge, and described multiphase filter is five phase filters, and described heterogeneous photovoltaic DC-to-AC converter alsoComprise SPWM module, PMU module, MPPT module and computing module, wherein said SPWM module is passed throughControl line connects with described five phase inversion bridgings, and described PMU module connects by holding wire and described SPWM moduleConnect, described MPPT module is connected with described PMU module by holding wire, and described computing module and instituteState the electrical connection of MPPT module;
When operation, described MPPT module is come real by controlling the break-make of IGBT pipe in DC/DC moduleThe tracking of existing described heterogeneous photovoltaic DC-to-AC converter maximum power point, described PMU module sends instruction to describedSPWM module, described SPWM module passes through to control the IGBT pipe break-make of described five phase inverter bridge, therebyObtain the voltage signal of expecting.
3. heterogeneous photovoltaic DC-to-AC converter according to claim 2, is characterized in that, described heterogeneous photovoltaicInverter has 1/4 working method and 2/3 working method; Wherein
Described 1/4 working method refers at a time, and the upper brachium pontis of described five phase inverter bridge has one to be conducted,Lower brachium pontis has four to be conducted, or the upper brachium pontis of described five phase inverter bridge has four to be conducted, and lower brachium pontis has one to lead mutuallyLogical; And
Described 2/3 working method refers at a time, and the upper brachium pontis of described five phase inverter bridge has two to be conducted,Lower brachium pontis has three to be conducted, or the upper brachium pontis of described five phase inverter bridge has three to be conducted, and lower brachium pontis has two-phase to leadLogical.
4. heterogeneous photovoltaic DC-to-AC converter according to claim 2, is characterized in that, in described 1/4 workDo in mode and 2/3 working method, upper brachium pontis conducting mutually adjacent, and lower brachium pontis conducting is mutually adjacent.
5. heterogeneous photovoltaic DC-to-AC converter according to claim 2, is characterized in that, described SPWM mouldPiece is provided with the circuit of carrying out following process:
(1) set up the switching equation of heterogeneous photovoltaic DC-to-AC converter: S=[Sa，Sb，Sc，Sd，Se], wherein,Sk=1 represents that on photovoltaic DC-to-AC converter a phase brachium pontis, switch conduction, lower switch turn-off, Sk=0 represents upper switchShutoff, lower switch conduction, wherein k=a, b, c, d, or e;
(2) set up the pole tension equation of heterogeneous photovoltaic DC-to-AC converter: uk0＝SkUd-Ud/2；
(3) set up the voltage vector equation of heterogeneous photovoltaic DC-to-AC converter:
(4) obtain 32 voltage vectors of heterogeneous photovoltaic DC-to-AC converter, these 32 voltage vectors comprise greatlyVector ULi, i be >=1 and≤10 integer, middle vector UMj, j be >=1 and≤10 integer, little arrowAmount USn, n be >=1 and≤10 integer, and two zero vector U0, wherein these 32 voltage vectorsBe scattered in 10 sectors, each sector comprises two large vectors, two middle vectors, two small vectorsAn and zero vector;
(5) synthesized reference voltage Uref: establish reference voltage UrefBe positioned at k sector, select UL(k+1)、UMk、UM(k+2)And a zero vector carrys out synthesized reference voltage Uref；
(6) obtain voltage UL(k+1)、UMk、UM(k+2)And U0Action time.
6. heterogeneous photovoltaic DC-to-AC converter according to claim 1, is characterized in that, described heterogeneous photovoltaicInverter also comprises direct current EMC wave filter, described direct current EMC wave filter be arranged on described dc circuit breaker withBetween described DC/DC converter, the input of wherein said direct current EMC wave filter and described dc circuit breakerOutput electrical connection, and the output of described direct current EMC wave filter and described DC/DC converter is defeatedEnter end electrical connection.
7. heterogeneous photovoltaic DC-to-AC converter according to claim 1, is characterized in that, described heterogeneous photovoltaicInverter also comprises and exchanges EMC wave filter, described interchange EMC wave filter be arranged at described multiphase filter andBetween described AC circuit breaker, the input of wherein said interchange EMC wave filter and described multiphase filterOutput electrical connection, and the output of described interchange EMC wave filter and the input of described AC circuit breakerElectrical connection.
8. a control method for heterogeneous photovoltaic DC-to-AC converter as claimed in claim 1, is characterized in that,Said method comprising the steps of:
(1) break-make of controlling the IGBT pipe in described DC/DC module realizes described heterogeneous photovoltaicThe tracking of inverter maximum power point;
(2) set up the switching equation of heterogeneous photovoltaic DC-to-AC converter: S=[Sa，Sb，Sc，Sd，Se], wherein, Sk=1 represents switch conduction on photovoltaic DC-to-AC converter a phase brachium pontis, and lower switch turn-offs; Sa=0 represents upper switchTurn-off lower switch conduction, k=a, b, c, d or e;
(3) set up the pole tension equation of heterogeneous photovoltaic DC-to-AC converter: uk0＝SkUd-Ud/2；
(4) set up the voltage vector equation of heterogeneous photovoltaic DC-to-AC converter:
(5) obtain 32 voltage vectors of heterogeneous photovoltaic DC-to-AC converter, these 32 voltage vectors comprise greatlyVector ULi, i be >=1 and≤10 integer, middle vector UMj, j be >=1 and≤10 integer, little arrowAmount USn, n be >=1 and≤10 integer, and two zero vector U0, wherein these 32 voltage vectorsBe scattered in 10 sectors, each sector comprises two large vectors, two middle vectors, two small vectorsAn and zero vector;
(6) synthesized reference voltage Uref: establish reference voltage UrefBe positioned at k sector, select UL(k+1)、UMk、UM(k+2)An and zero vector U0Carry out synthesized reference voltage Uref；
(7) obtain voltage UL(k+1)、UMk、UM(k+2)And U0Action time.
9. control method according to claim 8, is characterized in that, obtains electricity by following stepsPress UL(k+1)、UMk、UM(k+2)And U0Action time:
Be located at a switch periods TsThe action time of interior k vector is Tk, set up in k sector and vowAmount equilibrium equation:
T s U r e f = T L ( k + 1 ) U L ( k + 1 ) + T M k U M K + T M ( k + 2 ) U M ( K + 2 ) T s = T L ( k + 1 ) + T M k + T M ( k + 2 ) + T 0
Thereby obtain TL(k+1)、T(M+2)k、TMkAnd T0。
10. control method according to claim 8, is characterized in that, voltage UL(k+1)、UMk、UM(k+2)And U0Sequence of operation be: UMk→UL(k+1)→UM(k+2)→U0→UM(k+2)→UL(k+1)→UMk。
CN201610169902.7A 2016-03-23 2016-03-23 Multiphase photovoltaic inverter and control method thereof Pending CN105610344A (en)

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