CN203708129U - Single-phase cascade multi-level photovoltaic inverter and control system thereof - Google Patents

Single-phase cascade multi-level photovoltaic inverter and control system thereof Download PDF

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Publication number
CN203708129U
CN203708129U CN201320716866.3U CN201320716866U CN203708129U CN 203708129 U CN203708129 U CN 203708129U CN 201320716866 U CN201320716866 U CN 201320716866U CN 203708129 U CN203708129 U CN 203708129U
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module
control system
controller
sub
communication unit
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李泽军
王翠
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Hunan Institute of Technology
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Hunan Institute of Technology
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    • 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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Abstract

The utility model discloses a single-phase cascade multi-level photovoltaic inverter and a control system thereof. The single-phase cascade multi-level photovoltaic inverter comprises n PV arrays, n DC-DC modules, n DC-AC modules and the control system. The control system comprises a main controller, a communication unit, n sub-controllers, n first drivers, and n second drivers. The communication unit comprises n+1 electro-optical conversion modules, a first optical fiber coupler, n+1 photoelectric conversion modules, and a second optical fiber coupler. In the single-phase cascade multi-level photovoltaic inverter, an equal-voltage cascade inversion circuit is composed of a plurality of inverters, the current and voltage taken by switches of each level are low, so that convenient element choosing, low price, no voltage equalization and current equalization requirements, capability in employing an n+1 redundant design scheme, and improvement is circuit reliability and stability are achieved. The single-phase cascade multi-level photovoltaic inverter is simple in structure, convenient to operate, and high in energy utilization rate.

Description

Single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof
Affiliated technical field
The utility model relates to photovoltaic reverse power generation device field, refers in particular to a kind of single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof that photo-voltaic power generation station uses of specializing in.
Background technology
Along with the development of human society, the consumption of the energy constantly increases, and fossil energy in the world will reach capacity one day.Meanwhile, due to a large amount of burning fossil energies, the biological environment in the whole world goes from bad to worse, and the mankind's survival and development have been formed to very large threat.Under such background, solar energy, as a kind of regenerative resource of flood tide, has caused people's great attention, and national governments are progressively promoting the development of solar energy power generating industry.
In domestic and international market, the version of photovoltaic generating system is divided into two classes, and a kind of is system---the non-scheduling formula photovoltaic generating system that does not contain storage battery; Another kind is the system that contains storage battery---can dispatch formula photovoltaic generating system.Non-scheduling formula photovoltaic generating system need not storage battery, save investment, reduce the environmental pollution that loss that charge and discharge device causes and old and useless battery treatment bring, based on this, the free from controversy leading position that has occupied market of non-scheduling formula photovoltaic generating system, reach more than 90%, become the trend in this field.Non-scheduling formula photovoltaic generating system is mainly divided into four kinds of structures: (1) Industrial Frequency Transformer isolation method, (2) high frequency transformer isolation method, (3) high frequency transless mode, (4) transless mode.
Above-mentioned four kinds of photovoltaic DC-to-AC converters are all two-level inverters, for high-power photovoltaic generating system, the inversion efficiency of two level inverse conversion technology is low, du/dt and di/dt stress are large, common-mode voltage is high, semiconductor power device switching frequency is high, switching loss is large, output voltage waveforms aberration rate (thd) increases, harmonic content is high, electromagnetic interference (EMI) is serious, and the heat radiation difficulty of semiconductor power device etc., especially for desert photo-voltaic power generation station, carry out the remote transmission of electric energy, must use step-up transformer.
Single-phase cascading multiple electrical level photovoltaic DC-to-AC converter and control system thereof adopt the connection in series-parallel of some photovoltaic battery panels to obtain independently direct voltage source, utilize control system to control independent DC power supply, make each DC power output voltage equal and opposite in direction, and each independently direct voltage source is carried out to inversion, then inverting output terminal series connection can be met to electrical network required voltage.Single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof can independently be controlled the power stage of each unit, make in photovoltaic inverting system cell panel be operated in also can to carry out independently MPPT maximum power point tracking (Maximum Power Point Tracking is called for short mppt) under unmatched state to control.Single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof can obtain satisfied output effect in the situation that switching frequency is lower, not only reduce switching loss, reduce filter volume, saved filter cost, effectively improved the efficiency of power conversion system simultaneously.The redundancy properties of single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof, can overcome because intensity of illumination weakens the output voltage causing and reduce, and the excursion of output voltage amplitude is reduced, and output voltage waveforms quality improves.
Utility model content
The technical problem that the utility model solves is: the technical problem existing for prior art, the utility model proposes a kind of simple in structure, with low cost, adopt cascade inverter circuit improving output voltage and power, each inverter bridge of series connection is adopted single-phase cascade connection multi-level photovoltaic DC-to-AC converter and the control system thereof of distributed control simultaneously.
In order to solve the problems of the technologies described above, the solution the utility model proposes is: single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof, it is characterized in that: it comprises PV array (being photovoltaic battery array), DC-DC module, DC-AC module, control system, described PV array is for generation of DC power supply, DC-DC module realizes DC voltage conversion and MPPT maximum power point tracking control (being that mppt controls), DC-AC module realizes invert function, described PV array output dc voltage after capacitor filtering as the power supply of DC-DC module, DC-DC module is controlled by control system, realizing mppt controls, and the output voltage that guarantees each DC-DC module equates, meet the supply voltage requirement that waits voltage cascaded multilevel inverter, DC-DC module output voltage after capacitor filtering as the power supply of DC-AC module, DC-AC module is controlled by control system, the output series connection of multiple DC-AC modules, after inductor filter, export.
Described control system comprises master controller, communication unit, multiple sub-controller and driver, master controller is connected with each sub-controller by communication unit, the output of sub-controller is connected with driver, driver comprises driver one and driver two, driver one is connected with DC-DC module, control for the voltage transformation and the mppt that realize DC-DC module, driver two is connected with DC-AC module, for realizing the inversion of DC-AC module.Described master controller is unified to regulate to whole control system, and in the time that system breaks down, protection is action in time; Master controller sends instruction to DC-DC module, requires each DC-DC module output voltage equal and opposite in direction; Master controller is by detection of grid voltage signal, to each DC-AC module Synchronization Control.First sub-controller detects input voltage and the output current of DC-DC module, calculates the ON time of the switching tube of DC-DC module, provides pwm control signal, and the mppt that realizes photovoltaic cell controls; Then sub-controller, according to the instruction of master controller, calculates the switching tube service time of each DC-AC inversion unit and provides pwm signal; Described master controller and sub-controller form two-stage distributed control system.
Described communication unit comprises electrooptic conversion module, fiber coupler one, photoelectric conversion module and fiber coupler two, the control signal that electrooptic conversion module sends master controller is converted to light signal, light signal is converted to n road light signal by fiber coupler Yi Ba mono-road light signal, n road light signal is given respectively n photoelectric conversion module, light signal is reduced into the signal of telecommunication, for controlling n sub-controller; N electrooptic conversion module is converted to light signal the fault-signal of n sub-controller feedback, and n light signal merged into a road light signal by fiber coupler two, and light signal is reduced into the signal of telecommunication through photoelectric conversion module, and fault-signal is passed to master controller.
Compared with prior art, the utility model has the advantage of:
1, the utility model adopts the voltage cascade inverter circuits such as multiple inverter compositions, electric current and voltage strength that the switching device of every grade bears are low, not only the selection of components and parts is convenient but also cheap, without all requirements of pressure, current-sharing, the damage of any one-level can not affect the work of other grade, n+1 Redundancy Design scheme be can adopt easily, circuit reliability and stability improved;
2, the utility model can be realized the mppt control of each PV array, and the conversion efficiency of direct voltage is high;
3, control system of the present utility model adopts the structure of a master controller and multiple sub-controllers, between master controller and multiple sub-controller, adopts optical fiber communication, makes photovoltaic inverting system form a two-stage distributed control system;
4, the utility model utilizes mains voltage signal to realize the synchronous and coordination between each DC-AC module, and communication system need not be controlled in real time to the waveform of inverter, has improved the reliability of control system, has saved cost.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is further illustrated.
Fig. 1 is structural framing schematic diagram of the present utility model;
Fig. 2 is control system frame structure schematic diagram of the present utility model;
Fig. 3 is main circuit structure figure of the present utility model;
Fig. 4 is specific embodiment of the utility model.
Marginal data
1, PV array 2, DC-DC module 3, DC-AC module
4, control system 41, master controller 42, communication unit
421, electrooptic conversion module 422, fiber coupler 1, photoelectric conversion module
424, fiber coupler 2 43, sub-controller 44, driver one
45, driver two
Symbol description
C 1, C 2, C 3, C n, C 1', C 2', C 3', C n': filter capacitor
Q 1、Q 2、Q n、Q 11、Q 12、Q 13、Q 14、Q 21、Q 22、Q 23、Q 24、Q n1、Q n2、Q n3、Q n4：IGBT
L, L 1, L 2, L n: inductance D 1, D 2, D n: diode
Embodiment
Below with reference to the drawings and specific embodiments, the utility model is described in further details.
As shown in Figure 1, single-phase cascade connection multi-level photovoltaic DC-to-AC converter of the present utility model and control system thereof, it comprises n PV array (1), a n DC-DC module (2), a n DC-AC module (3), control system (4), described control system (4) is made up of master controller (41), communication unit (42), a n sub-controller (43), a n driver one (44) and n driver two (45), and n PV array (1) output voltage is respectively through capacitor C 1, C 2..., C nafter filtering, be connected with n DC-DC module (2), n DC-DC module (2) output voltage is respectively through capacitor C 1', C 2' ..., C nafter ' filtering, be connected with n DC-AC module (3), n DC-AC module (3) output is connected successively, after inductance L filtering, is connected with electrical network from the output of M, N end.The connection of PV array (1), DC-DC module (2) and DC-AC module (3) as shown in Figure 3.
Shown in Figure 2, control system (4) comprises master controller (41), communication unit (42) and n sub-controller (43), n driver one (44) and n driver two (45), communication unit (42) comprises n+1 electrooptic conversion module (421), fiber coupler one (422), n+1 photoelectric conversion module (423) and fiber coupler two (424), master controller (41) is connected with the input of the sub-controller (43) of n by communication unit (42), the output of sub-controller (43) is connected with n driver two (45) with n driver one (44), the output signal of n driver one (44) is directly received the switching device of each DC-DC module (2), the output signal of n driver two (45) is directly received each switching device of each DC-AC module (3), the output current of DC-DC module (2) is delivered to sub-controller (43) by current transformer, the input voltage of DC-DC module (2) is delivered to sub-controller (43) by voltage transformer.
Referring to Fig. 3, each DC-DC module (2) is by a switching device Q i(i gets 1,2 ..., n) and inductance L i(i gets 1,2 ..., n) and diode D i(i gets 1,2 ..., n) composition, each DC-AC module (3) is by four switching device Q i1, Q i2, Q i3, Q i4(i gets 1,2 ..., n), composition, output inductance L strobes.
Shown in Figure 4, the main circuit of the present embodiment has 3 PV arrays (1), 3 DC-DC modules (2), 3 DC-AC modules (3), and the output of 3 DC-AC modules (3) is composed in series three-stage inverter.In the present embodiment, communication unit (42) adopts optical fiber communication, and master controller (41) and sub-controller (43) all adopt take TMS320F240 as basic embedded control unit.In the present embodiment, control system (4) is made up of 1 master controller (41), 1 communication unit (42) and 3 sub-controllers (43) and one (44), 3 driver two (45) of 3 drivers; Each DC-DC module (2) and corresponding DC-AC module (3) thereof share an independently sub-controller (43); it act as the control and protection of realizing DC-DC module (2) and DC-AC module (3); produce the driving signal of each switching device, sub-controller (43) detects input voltage signal and the output current signal of DC-DC module (2) and for realizing, the mppt of PV array (1) is controlled.DC-AC module (3) voltage over the ground floats, therefore, sub-controller (43) mutually between and they on electric, isolate over the ground, between master controller (41) and sub-controller (43), adopt optical fiber communication.Sub-controller (43) and master controller (41) are all take TMS320F240 as basic embedded controller, and they form respectively the master controller (41) of the 1st grade and the sub-controller (43) of the 2nd grade.
When work, the advanced row data processing of master controller (41) of the 1st grade, control signal is delivered to respectively to the sub-controller (43) that is positioned at the 2nd grade by the optical fiber communication of communication unit (42) again, sub-controller (43) is according to the control signal of master controller (41), control respectively DC-DC module (2) and DC-AC module (3), the output series winding of DC-AC module (3), M, N holds output AC voltage, at work, sub-controller (43) detects input voltage and the output current of DC-DC module (2) and realizes the mppt control to PV array (1), master controller (41) is by detecting the voltage feedback signal of inverter, transmit control signal to each sub-controller (43), each sub-controller (43) is adjusted the operating state of corresponding DC-DC module (2) and DC-AC module (3).Fault-signal from DC-DC module (2) and DC-AC module (3) is delivered to master controller (41) by sub-controller (43) respectively.
These are only an embodiment of the present utility model, the utility model is not limited to above-described embodiment, as long as belong to the technical scheme under the utility model design, all should belong to protection range of the present utility model.

Claims (2)

1. single-phase cascade connection multi-level photovoltaic DC-to-AC converter and control system thereof, it is characterized in that: it comprises n PV array (1), a n DC-DC module (2), a n DC-AC module (3), control system (4), and described control system (4) is made up of master controller (41), communication unit (42), a n sub-controller (43), a n driver one (44) and n driver two (45); Described sub-controller (43) is connected with driver one (44), and the driving signal of generation is used for controlling DC-DC module (2); Described sub-controller (43) is connected with driver two (45), and the driving signal of generation is used for controlling DC-AC module (3); Described communication unit (42) adopts optical fiber communication, comprise n+1 electrooptic conversion module (421), fiber coupler one (422), a n+1 photoelectric conversion module (423) and fiber coupler two (424), the control signal that master controller (41) produces is sent to each sub-controller (43) by communication unit (42), and each sub-controller (43) is sent master controller (41) fault-signal back to by communication unit (42).
2. single-phase cascade connection multi-level photovoltaic DC-to-AC converter according to claim 1 and control system thereof, it is characterized in that: described master controller (41) and sub-controller (43) form two-stage distributed control system, utilize mains voltage signal realize the synchronous of each DC-AC module and coordinate.
CN201320716866.3U 2013-11-08 2013-11-08 Single-phase cascade multi-level photovoltaic inverter and control system thereof Expired - Fee Related CN203708129U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105743336A (en) * 2014-12-10 2016-07-06 沈阳远大电力电子科技有限公司 Cascade type high voltage frequency converter and main control system thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105743336A (en) * 2014-12-10 2016-07-06 沈阳远大电力电子科技有限公司 Cascade type high voltage frequency converter and main control system thereof
CN105743336B (en) * 2014-12-10 2019-08-02 沈阳远大电力电子科技有限公司 A kind of cascaded high-voltage frequency converter and its master control system

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Granted publication date: 20140709

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