CN103094922B - Two-level type single-phase grid-connected photovoltaic power generation control method - Google Patents

Two-level type single-phase grid-connected photovoltaic power generation control method Download PDF

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CN103094922B
CN103094922B CN201310009315.8A CN201310009315A CN103094922B CN 103094922 B CN103094922 B CN 103094922B CN 201310009315 A CN201310009315 A CN 201310009315A CN 103094922 B CN103094922 B CN 103094922B
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voltage
phase inversion
boost
inversion circuit
phase
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CN103094922A (en
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任碧莹
孙向东
张琦
安少亮
宋卫章
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Xian University of Technology
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Xian University of Technology
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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Abstract

The invention discloses a two-level type single-phase grid-connected photovoltaic power generation control method aimed at a grid-connected photovoltaic power generation inverter circuit formed by a BOOST converter, a single-phase inverter circuit and a filter. The BOOST converter has two work modes which are a work mode of a BOOST non-work zone and a work mode of a BOOST work zone. The single-phase inverter circuit achieves the function that high-power-factor harmonic current is injected into a power grid through maximum power point tracing outer-ring control and inverter output current inner-ring control. According to the two-level type single-phase grid-connected photovoltaic power generation control method, the BOOST converter does not work for a part of time within a half power grid power frequency circle, so that switching consumption is avoided, and the power of the whole system is further improved.

Description

The single-phase photovoltaic grid-connected electricity-generating control method of a kind of two-stage type
Technical field
The invention belongs to solar energy power generating control technology field, relate to the single-phase photovoltaic grid-connected electricity-generating control method of a kind of two-stage type.
Background technology
Solar energy resources is inexhaustible, nexhaustible, and photovoltaic generation obtains fast development as one of the generation technology of Solar use.With regard to current technical merit, monolithic photovoltaic battery panel output voltage is lower, needs polylith photovoltaic battery panel to carry out series connection to form photovoltaic branch road, forms photovoltaic array by identical photovoltaic branch circuit parallel connection.The direct current that photovoltaic array produces just can be converted to alternating current through combining inverter and inject electrical network.Under the prerequisite of identical power output, the raising of combining inverter efficiency means can install some photovoltaic battery panels less, thus reduces the equipment cost of whole photovoltaic generating system.
Inverter circuit efficiency of generating electricity by way of merging two or more grid systems is higher, and due to photovoltaic array output voltage relatively low, therefore BOOST booster converter and the single-phase inversion circuit of adopting forms the single-phase photovoltaic grid-connected power-generation inversion circuit of two-stage type more.For above-mentioned two-stage type circuit, when photovoltaic array output voltage is lower than electrical network crest voltage, usual way is: take the power switch of BOOST booster converter to work always, with single-phase inversion control circui cooperation, to ensure that the output voltage stabilization of BOOST booster converter is at a certain DC voltage value, this DC voltage value is higher than electrical network crest voltage, its objective is and ensures that the electric energy that photovoltaic array produces injects electrical network smoothly.Because the power switch of now BOOST booster converter works always, therefore the efficiency of whole system is affected.
Summary of the invention
The object of this invention is to provide the single-phase photovoltaic grid-connected electricity-generating control method of a kind of two-stage type, the power switch solving BOOST booster converter in prior art is always in running order, switching loss is caused obviously to increase, the problem that whole system efficiency is not not fully exerted.
The technical solution adopted in the present invention is, the single-phase photovoltaic grid-connected electricity-generating control method of a kind of two-stage type,
Form a parallel network power generation circuit, comprise the BOOST booster converter be connected with photovoltaic array, BOOST booster converter is connected successively with single-phase inversion circuit, filter circuit, and filter circuit is grid-connected with public electric wire net to be again connected,
Utilize above-mentioned parallel network power generation inverter circuit, single-phase inversion circuit keeps a kind of control mode always, and described BOOST booster converter exists two kinds of mode of operations, the mode of operation of the mode of operation namely between BOOST dead zone and BOOST operation interval:
Mode of operation between described BOOST dead zone refers in the time period of photovoltaic array output voltage values V1 higher than the absolute value of electrical network instantaneous voltage, the power switch of BOOST booster converter is in off state, and now single-phase inversion circuit input direct voltage V2 equals photovoltaic array output voltage V1;
The mode of operation of described BOOST operation interval refers in the time period of photovoltaic array output voltage values V1 not higher than the absolute value of electrical network instantaneous voltage, the power switch of BOOST booster converter is in opening state, and now single-phase inversion circuit input direct voltage V2 is certain the given magnitude of voltage Vb higher than electrical network crest voltage.
The invention has the beneficial effects as follows: even photovoltaic array output voltage is lower than electrical network crest voltage, BOOST booster converter also needs work of always boosting unlike classical control method, but only just carries out boosting rectifier control when the absolute value of photovoltaic array output voltage not higher than electrical network instantaneous voltage.Therefore, there is part-time BOOST booster converter not work in half electrical network power frequency period, thus obviously reduce switching loss, whole system efficiency is further enhanced.
Accompanying drawing explanation
Fig. 1 is the single-phase photovoltaic grid-connected electricity-generating circuit block diagram of two-stage type that the inventive method relies on;
Fig. 2 is the connection diagram of the single-phase photovoltaic grid-connected electricity-generating circuit embodiment of two-stage type of the present invention;
Fig. 3 is that principle corresponding to the inventive method illustrates oscillogram;
Fig. 4 is the mode of operation deterministic process block diagram of the inventive method;
Fig. 5 is the control procedure block diagram of BOOST booster converter when BOOST operation interval of the inventive method;
Fig. 6 is the control principle block diagram of the single-phase inversion circuit in the inventive method.
In figure, 1. photovoltaic array, 2.BOOST booster converter, 3. single-phase inversion circuit, 4. filter circuit, 5. public electric wire net;
In addition, I1 represents photovoltaic array output current,
V1 represents photovoltaic array output voltage,
V2 represents single-phase inversion circuit input direct voltage,
I3 represents single-phase inversion circuit output current,
V4 represents public electric wire net voltage,
The reference value of single-phase inversion circuit input direct voltage when constant Vb is BOOST operation interval,
C1 represents photovoltaic array output filter capacitor,
C2 represents single-phase inversion circuit input direct-current filter capacitor,
D1 represents anti-reverse charging power diode,
D2 represents the diode in BOOST booster converter,
L1 represents the inductance in BOOST booster converter,
L2 represents ac filter inductance,
S1-S4 represents four power switchs in single-phase inversion circuit,
S5 represents the power switch in BOOST booster converter.
Embodiment
With reference to Fig. 1, it is the block diagram of the parallel network power generation circuit that the single-phase photovoltaic grid-connected electricity-generating control method of two-stage type of the present invention relies on, its structure is, comprise the BOOST booster converter 2 be connected with photovoltaic array 1, BOOST booster converter 2 is connected successively with single-phase inversion circuit 3, filter circuit 4, and filter circuit 4 is connected with public electric wire net 5 is grid-connected again.
Above-mentioned BOOST booster converter 2 is as prime, single-phase inversion circuit 3 is as rear class, the output of BOOST booster converter 2 connects the input of single-phase inversion circuit 3, the output of single-phase inversion circuit 3 connects the input of filter circuit 4, and the output of filter circuit 4 connects the input of public electric wire net 5.
BOOST booster converter 2 selects classical BOOST booster converter, or with the BOOST booster converter of zero voltage transition (ZVT) Sofe Switch function.
Single-phase inversion circuit 3 selects the full bridge inverter of classical bipolar pulse width modulated (PWM), or has the various inverter circuits of single-polarity PWM of common mode current inhibit feature.
The one of L-type filter, LC mode filter or LCL type filter selected by filter circuit 4.
With reference to Fig. 2, it is a kind of embodiment circuit connection block diagram of the single-phase photovoltaic grid-connected electricity-generating control method of two-stage type of the present invention, BOOST booster converter 2 selects classical BOOST booster converter, single-phase inversion circuit 3 selects the full bridge inverter of classical bipolar pulse width modulated (PWM), and L-type filter selected by filter circuit 4.
With reference to Fig. 3, it is the principle explanation oscillogram corresponding to control method embodiment of the present invention, interval at 0-t1, t2-t3 is interval, t4-t5 is interval, t6-t7 is interval, t8-t9 interval in, photovoltaic array output voltage values V1 is higher than the absolute value of electrical network instantaneous voltage, its power switch pipe is failure to actuate, and therefore these intervals are all between the dead zone of BOOST booster converter; And interval at t1-t2, t3-t4 is interval, t5-t6 is interval, t7-t8 interval in, photovoltaic array output voltage values V1 is not higher than the absolute value of electrical network instantaneous voltage, its power switch pipe action, therefore these intervals are all the operation intervals of BOOST booster converter.Between the dead zone for BOOST booster converter, single-phase inversion circuit input direct voltage V2 equals photovoltaic array output voltage V1; For the operation interval of BOOST booster converter, single-phase inversion circuit input direct voltage V2 is certain the given magnitude of voltage Vb(such as 380V higher than electrical network crest voltage).Because line voltage to go round and begin again change by power frequency period, therefore line voltage is after taking absolute value, total in every half power frequency period exist between two BOOST dead zones and a BOOST operation interval, and between BOOST dead zone, BOOST switching loss reduces to 0, obviously reduces relative to BOOST switching loss under conventional control mode.
The operation principle of the single-phase photovoltaic grid-connected electricity-generating control method of two-stage type of the present invention is:
With reference to Fig. 4, be that the mode of operation of the single-phase photovoltaic grid-connected electricity-generating control method of two-stage type of the present invention judges block diagram.Line voltage V4 is through taking absolute value computing, obtain the absolute value of line voltage V4, it and photovoltaic array output voltage V1 compare, and obtain BOOST booster converter mode of operation judged result, and the system that namely draws is between BOOST dead zone or BOOST operation interval two kinds of mode of operations.
When system is in the mode of operation between BOOST dead zone, power switch S5 in BOOST booster converter 2 is prohibited, be in off state always, the now inductance L 1 of the output voltage of photovoltaic array 1 in anti-reverse charging power diode D1, photovoltaic array output filter capacitor C1, BOOST booster converter and diode D2, directly as single-phase inversion circuit input direct voltage V2;
When system is in the mode of operation of BOOST operation interval, its control block diagram is with reference to Fig. 5, its inverter circuit input direct voltage reference value constant Vb is as the reference value of single-phase inversion circuit input direct voltage V2, the single-phase inversion circuit input direct voltage V2 of it and actual samples is through subtraction, obtain their error amounts of two, this error amount is through overvoltage PI closed loop control algorithm, again through PWM output signal process, the power switch S5 come in control BOOST booster converter carries out switch motion, realize the magnitude of voltage that BOOST boost converter output voltage is stabilized in constant Vb.
Be in the mode of operation of BOOST operation interval regardless of the single-phase photovoltaic grid-connected power-generation inversion circuit of two-stage type, be still in the mode of operation between BOOST dead zone, the control mode of single-phase inversion circuit 3 wherein remains unchanged always.
With reference to Fig. 6, the control mode of single-phase inversion circuit 3 is, by the sampling to photovoltaic array output current I1 and photovoltaic array output voltage V1, draws single-phase inversion circuit output current amplitude reference according to MPPT maximum power point tracking algorithm, line voltage V4 draws synchronous rotary angle through digital phase-locked loop, sinusoidal calculations is carried out to this synchronous rotary angle and draws unit sinusoidal reference signal, single-phase inversion circuit output current amplitude reference and unit sinusoidal reference signal carry out multiplying, draw single-phase inversion circuit reference output current, this reference output current carries out subtraction with actual single-phase inversion circuit output current, draw current error, this current error is through closed-loop current control algorithm, draw the PWM output signal of the S1-S4 power switch for controlling single-phase inversion circuit, thus produce the current signal consistent with electric network voltage phase.
Described MPPT maximum power point tracking algorithm can be disturbance observation or other algorithm known.
Described closed-loop current control algorithm can be track with zero error or other current known algorithms.
In sum, BOOST booster converter 2 determines whether work according to the magnitude relationship of the absolute value of photovoltaic array output voltage and electrical network instantaneous voltage, and whether the input voltage of single-phase inversion circuit changes respectively along with the work of BOOST booster converter between certain given magnitude of voltage and photovoltaic array output voltage two magnitudes of voltage.Single-phase inversion circuit 3 is always in running order, the sinusoidal current being controlled High Power Factor by the control of MPPT maximum power point tracking outer shroud and inverter output current inner ring injects electrical network function, namely its control outer shroud is MPPT maximum power point tracking algorithm, its output valve exports reference current amplitude as inversion, the synchronous rotary angular unit sine value that it and the digital phase-locked loop based on line voltage produce is multiplied, reference current is exported as inversion, this inversion exports the input of difference as closed-loop current control algorithm of the inverter output current of reference current and actual feedback, the inner ring realizing single-phase inversion circuit controls.
The essential meaning of the inventive method is, when photovoltaic array output voltage is lower than line voltage peak value, at single-phase inversion circuit by the basis that MPPT maximum power point tracking outer shroud controls and inverter output current inner ring controls, utilize the magnitude relationship of photovoltaic array output voltage and electrical network instantaneous voltage, work when BOOST booster converter is in half electrical network power frequency period, time and do not work, therefore compared with in running order all the time with classical BOOST booster converter, the switching loss of the BOOST booster converter in the inventive method obviously reduces, the efficiency of whole system is promoted significantly, be specially adapted to photovoltaic array output voltage lower than the single-phase photovoltaic grid-connected electricity-generating circuit of two-stage type in electrical network crest voltage situation.

Claims (1)

1. the single-phase photovoltaic grid-connected electricity-generating control method of two-stage type, is characterized in that:
Form a parallel network power generation inverter circuit, comprise the BOOST booster converter (2) be connected with photovoltaic array (1), BOOST booster converter (2) is connected successively with single-phase inversion circuit (3), filter circuit (4), filter circuit (4) is connected with public electric wire net (5) is grid-connected again
Utilize above-mentioned parallel network power generation inverter circuit, single-phase inversion circuit (3) keeps a kind of control mode always, and there are two kinds of mode of operations, the mode of operation of the mode of operation namely between BOOST dead zone and BOOST operation interval in described BOOST booster converter (2):
Mode of operation between described BOOST dead zone refers in the time period of photovoltaic array output voltage values V1 higher than the absolute value of electrical network instantaneous voltage, the power switch of BOOST booster converter (2) is in off state, and now single-phase inversion circuit input direct voltage V2 equals photovoltaic array output voltage V1;
The mode of operation of described BOOST operation interval refers in the time period of photovoltaic array output voltage values V1 not higher than the absolute value of electrical network instantaneous voltage, the power switch of BOOST booster converter (2) is in opening state, now single-phase inversion circuit input direct voltage V2 is certain the given magnitude of voltage Vb higher than electrical network crest voltage
The control mode of described single-phase inversion circuit (3) is, by the sampling to photovoltaic array output current I1 and photovoltaic array output voltage V1, draws single-phase inversion circuit output current amplitude reference according to MPPT maximum power point tracking algorithm, line voltage draws synchronous rotary angle through digital phase-locked loop, sinusoidal calculations is carried out to this synchronous rotary angle and draws unit sinusoidal reference signal, single-phase inversion circuit output current amplitude reference and unit sinusoidal reference signal carry out multiplying, draw single-phase inversion circuit reference output current, this reference output current carries out subtraction with actual single-phase inversion circuit output current I3, draw current error, this current error is through closed-loop current control algorithm, draw the PWM output signal of the S1-S4 power switch for controlling single-phase inversion circuit (3), thus produce the current signal consistent with electric network voltage phase.
CN201310009315.8A 2013-01-11 2013-01-11 Two-level type single-phase grid-connected photovoltaic power generation control method Expired - Fee Related CN103094922B (en)

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CN103532127A (en) * 2013-10-29 2014-01-22 哈尔滨工业大学 Control method of DC active filter for micro DC-grid
CN104079007B (en) * 2014-03-06 2016-08-24 西安理工大学 The distributed photovoltaic of suppression low pressure feeder line overvoltage generates electricity by way of merging two or more grid systems control method
JP6295782B2 (en) * 2014-03-31 2018-03-20 株式会社安川電機 Power conversion device, power generation system, control device, and power conversion method
CN104270022B (en) * 2014-09-30 2017-02-15 马鞍山市安工大工业技术研究院有限公司 Photovoltaic grid connected inversion circuit, switch control circuit and control method
CN106828123B (en) * 2017-02-10 2023-04-07 西南交通大学 High-speed railway traction power supply system with distributed photovoltaic power supply and control method
US10536002B2 (en) * 2017-05-12 2020-01-14 Futurewei Technologies, Inc. Power systems with inverter input voltage control
CN111740636B (en) * 2020-06-29 2021-07-30 国网浙江省电力有限公司温州供电公司 Bidirectional inverter and remote charging and discharging maintenance system
CN114865709B (en) * 2022-07-07 2022-09-30 浙江日风电气股份有限公司 Bus voltage control method, device and medium for single-phase photovoltaic inverter

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CN100508327C (en) * 2007-06-08 2009-07-01 清华大学 Photovoltaic three-phase grid control method for fast and steadily implementing maximal power tracing
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