CN107666242A - A kind of 20kW three-level photovoltaic grid-connected inverters - Google Patents

A kind of 20kW three-level photovoltaic grid-connected inverters Download PDF

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Publication number
CN107666242A
CN107666242A CN201610577692.5A CN201610577692A CN107666242A CN 107666242 A CN107666242 A CN 107666242A CN 201610577692 A CN201610577692 A CN 201610577692A CN 107666242 A CN107666242 A CN 107666242A
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CN
China
Prior art keywords
boost
level
grid
voltage
npc
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Pending
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CN201610577692.5A
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Chinese (zh)
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由国峰
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Individual
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Individual
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Priority to CN201610577692.5A priority Critical patent/CN107666242A/en
Publication of CN107666242A publication Critical patent/CN107666242A/en
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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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H02J3/385—
    • 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
    • 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

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

Abstract

The invention discloses a kind of 20kW three-level photovoltaic grid-connected inverters, including：Three 20kW three-level photovoltaic grid-connected inverters main circuit, Boost control systems and NPC inverter control system parts form.System uses to be designed without step-up transformer type, and Boost parts use Interleaving and Transformer Paralleling, and Converting Unit uses I type NPC three-level structures, system layer parameter is designed.For the neutral point voltage balance problem in NPC topological structures, it is proposed that change the discharge and recharge time adjustment mid-point voltage of electric capacity up and down in Boost circuit, be combined with the neutral-point-potential balance control algorithm based on bus capacitor Point Charge, and carried out verification experimental verification.Inverter control uses grid voltage orientation vector controlled, and the reliability of device by verification experimental verification.

Description

It is a kind of 20kW Three-level photovoltaic grid-connected inverter
Art
The present invention relates to a kind of photovoltaic combining inverter, more particularly to a kind of 20kW three-level photovoltaic grid-connected inverters.
Background technology
In recent years, distributed generation system has obtained quick development, and grid-connected photovoltaic system is exactly wherein most typical one kind, has obtained increasing concern in recent years.Compared with traditional two-level inverter, the clear superiorities such as there is NPC three-level photovoltaic inverters harmonic component to reduce, the horizontal reduction of component pressure and device volume are small, so as to be highly suitable for being applied in distributed energy resource system.To improve conversion efficiency, transformerless type three-level inverter is devised, it is mainly made up of Boost circuit, I type NPC inverter circuits and control circuit etc..Boost controls employ the control strategy that MPPT is combined with neutral point voltage balance, and inversion control is using direct current pressure ring and the bicyclic vector control strategy of electric current loop.
The content of the invention
In order to overcome the problem that conversion efficiency is low, harmonic components are big, device volume is not small enough, the present invention proposes a kind of 20kW three-level photovoltaic grid-connected inverters.
The technical solution adopted for the present invention to solve the technical problems is：
The present invention establishes system main circuit topology, devises control system by the analysis to existing photovoltaic DC-to-AC converter.20kW three-level photovoltaic grid-connected inverters include：Three 20kW three-level photovoltaic grid-connected inverters main circuit, Boost control systems and NPC inverter control system parts form.
The 20kW three-level photovoltaic grid-connected inverters main circuit is made up of four Boost circuit, I types NPC inverter, combining inverter and common-mode filter parts；
Three level schemes that the Boost control systems are controlled using difference, and two groups of Boost are in parallel；
The NPC inverter control system uses I type NPC three-level topology structures, in order to suppress inner and outer pipes unbalanced-voltage-division problem intrinsic in I type three-level topology structures, balance resistance of having been connected between two inner tubes.
The beneficial effects of the invention are as follows：For the neutral point voltage balance problem in NPC topological structures, propose the discharge and recharge time adjustment mid-point voltage for changing electric capacity up and down in Boost circuit, it is combined with the neutral-point-potential balance control algorithm based on bus capacitor Point Charge, so that the conversion efficiency of system improves, harmonic content reduces, and reduces the volume of inverter.The model machine of 20 kW three-level photovoltaic inverters of independent research, good grid-connected waveform and the voltage and current waveform of full power are obtained, and demonstrate the neutral balance control mode under two ways, it was confirmed that the feasibility of control strategy.
Brief description of the drawings
Fig. 1 20kW photovoltaic DC-to-AC converter main circuits.
Fig. 2 Boost control systems.
Fig. 3 single-phase inversion bridge arm schematic diagrames.
Specific embodiment
In Fig. 1, system main circuit topology is mainly boosted by Boost, DC links, I types NPC inverter, grid-connected wave filter, common-mode filter and grid-connected switch form.Wherein, Boost boost modules employ Boost three-level DC converters, and the voltage stress of its switching tube is the half of common Boost；Converting Unit adds balance resistance using I types NPC topologys, to ensure that inner tube reliable turn-off and inner and outer pipes are pressed；Output filter is divided into the grid-connected wave filters of LC and common-mode filter, wherein common-mode filter uses RC wave filters, the common point of wave filter is connected with dc bus midpoint, the common-mode voltage of inverter output is shared using RC wave filters and then reduces the common-mode voltage at grid-connected end.Rear class three-level inverter realizes active and idle uneoupled control using electric current, voltage double circle structure, its one side realizes watt current output control by stablizing middle dc voltage, and on the other hand giving instruction by reactive current realizes power factor regulation.Prime Boost circuit adjusts cell panel output voltage by MPPT algorithm, and the Pressure and Control of DC capacitor can be realized by phase adjusted.
In Fig. 2, Boost is using three level schemes of difference control, two groups of Boost parallel connections.The dutycycle of S1, S2 switching process is identical, but 180 ° of phase mutual deviation, and devise accordingly it is a kind of by adjust dutycycle realize busbar voltage neutral point balance method.Two-way Boost circuit output DC voltage is 800 V, and Converting Unit direct current pressure ring realizes the function of stable middle dc voltage.Boost input voltages i.e. PV cell panels input voltage can be controlled by adjusting dutycycle,.By gathering PV cell panels output current and voltage, the reference voltage of maximum power point is calculated using perturbation observation method for MPPT modules.The discharge and recharge time by changing electric capacity up and down can adjust the voltage of electric capacity, change switching tube S1 and S2 dutycycle, as long as ensure that two switching tube dutycycle sums keep constant, it is ensured that output voltage is constant, capacitor voltage equalizing can be both realized and the same dutycycle of another switching tube reduction by increasing the dutycycle of a switching tube, and does not influence output voltage.
In Fig. 3, using I type NPC three-level topology structures, in order to suppress inner and outer pipes unbalanced-voltage-division problem intrinsic in I type three-level topology structures, balance resistance of having been connected between two inner tubes.Analyzed with single-phase bridge arm, after adding balance resistance Rs, due to the presence of Rs resistance, make the leakage current in VT1 loops bigger than the leakage current in VT2 loop, therefore the additional electric current in VT2 loops can make VD5 have conducting, now VT1 E poles are clamped to central point, therefore now VT1 pipes and VT2 pipes divide equally DC bus-bar voltage UDC.Therefore voltage is clamped to 0.5UDC when the addition of Rs balance resistances turns off inner tube, reduces the overvoltage risk of inverter bridge leg.

Claims (4)

  1. A kind of 1. 20kW three-level photovoltaic grid-connected inverters, it is characterised in that：Including three 20kW three-level photovoltaic grid-connected inverters main circuit, Boost control systems and NPC inverter control system parts.
  2. It is 2. as claimed in claim 1, it is characterised in that the 20kW three-level photovoltaic grid-connected inverters main circuit is boosted by Boost, DC links, I types NPC inverter, grid-connected wave filter, common-mode filter and grid-connected switch form.
  3. It is 3. as claimed in claim 1, it is characterised in that three level schemes that the Boost control systems Boost is controlled using difference, and be made up of two groups of Boost parallel connections.
  4. It is 4. as claimed in claim 1, it is characterised in that the NPC inverter control system is in order to suppress inner and outer pipes unbalanced-voltage-division problem intrinsic in I type three-level topology structures, balance resistance of having been connected between two inner tubes.
CN201610577692.5A 2016-07-21 2016-07-21 A kind of 20kW three-level photovoltaic grid-connected inverters Pending CN107666242A (en)

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CN201610577692.5A CN107666242A (en) 2016-07-21 2016-07-21 A kind of 20kW three-level photovoltaic grid-connected inverters

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201610577692.5A CN107666242A (en) 2016-07-21 2016-07-21 A kind of 20kW three-level photovoltaic grid-connected inverters

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CN107666242A true CN107666242A (en) 2018-02-06

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109347331A (en) * 2018-12-05 2019-02-15 深圳市英可瑞科技股份有限公司 A kind of tri-level switch power-supply system and its bus voltage eqaulation control method
CN113489326A (en) * 2021-08-20 2021-10-08 青岛鼎信通讯股份有限公司 Two-stage DC/AC bidirectional conversion device applied to energy router
CN113949259A (en) * 2021-12-21 2022-01-18 浙江日风电气股份有限公司 NPC three-level shutdown control method, device and system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109347331A (en) * 2018-12-05 2019-02-15 深圳市英可瑞科技股份有限公司 A kind of tri-level switch power-supply system and its bus voltage eqaulation control method
CN113489326A (en) * 2021-08-20 2021-10-08 青岛鼎信通讯股份有限公司 Two-stage DC/AC bidirectional conversion device applied to energy router
CN113949259A (en) * 2021-12-21 2022-01-18 浙江日风电气股份有限公司 NPC three-level shutdown control method, device and system
CN113949259B (en) * 2021-12-21 2022-03-01 浙江日风电气股份有限公司 NPC three-level shutdown control method, device and system

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Application publication date: 20180206