CN112398360B - Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof - Google Patents
Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof Download PDFInfo
- Publication number
- CN112398360B CN112398360B CN202011247021.5A CN202011247021A CN112398360B CN 112398360 B CN112398360 B CN 112398360B CN 202011247021 A CN202011247021 A CN 202011247021A CN 112398360 B CN112398360 B CN 112398360B
- Authority
- CN
- China
- Prior art keywords
- switching device
- current
- grid
- switching
- reference value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
-
- 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 single-phase three-level micro photovoltaic inverter and an open-loop control method and a system thereof. Furthermore, the open-loop control method is simple and effective, so that the inverter can realize the inversion control of the direct current of the photovoltaic panel, and outputs the sine alternating current which can meet the grid-connected requirement.
Description
Technical Field
The invention relates to the field of power electronic inverter driving and control, in particular to a single-phase three-level micro photovoltaic inverter and an open-loop control method and system thereof.
Background
With the rapid development of economic levels and industrial technologies worldwide, the energy demand is also increasing. Moreover, with the development of scientific technology, the non-regenerability of the traditional energy and the irreversible damage to the environment caused by the unlimited exploitation of the traditional energy, people tend to replace the traditional energy with a new clean and renewable energy. There are many types of renewable energy sources, including wind, water, geothermal, solar, etc., with solar being the most readily discovered and utilized renewable energy source. In recent years, as people pay more and more attention to power generation by using solar energy, photovoltaic power generation technology is rapidly developed.
The main core of the solar photovoltaic power generation system is a photovoltaic inverter which is used for inverting direct current generated by a solar photovoltaic panel into alternating current which can be accepted by a power grid and sending the alternating current into the power grid. In the conventional photovoltaic inversion system, a plurality of photovoltaic panels are connected in series to share one inverter, so that the size and power of the inverter are large, and the large power loss and the serious heating phenomenon are accompanied. In addition, due to the serial connection of the photovoltaic panels, when one photovoltaic panel fails or is shielded by a shadow and cannot normally work, the one photovoltaic panel cannot normally work, and the efficiency of photovoltaic power generation is reduced. Therefore, micro photovoltaic inverters have received much attention from researchers.
The micro photovoltaic inverter is a novel device which is modularized, can be used in a plug-and-play mode and can convert direct current of a single solar cell module into alternating current, and is born in American silicon valley. The research and application of the micro inverter are the leading edge and the hot spot of the current global power conversion technology research, and the micro inverter has the characteristics of high energy efficiency, long service life, small volume, high reliability, safe operation, convenient installation and the like, marks a new breakthrough of the photovoltaic technology, and has wide prospects in the aspect of various distributed photovoltaic power generation applications. But for the application of the micro photovoltaic inverter, a reasonable control algorithm is required to be designed to realize the conversion from direct current to alternating current.
Disclosure of Invention
The invention aims to provide a single-phase three-level micro photovoltaic inverter and an open-loop control method and a system thereof. Furthermore, the open-loop control method is simple and effective, so that the inverter realizes the inversion control of the direct current of the photovoltaic panel, and outputs the sine alternating current which can meet the grid-connected requirement.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a single-phase three-level micro photovoltaic inverter, comprising:
filtering and follow current inductance L 1 The input end of the filter is connected with the DC side photovoltaic panel, and the filtering and follow current inductor L 1 The photovoltaic power generation device is used for keeping the output current of the photovoltaic panel on the direct current side stable and reducing current ripples;
first clamping diode D A Its input terminal and the filtering and follow current inductance L 1 Is connected to the output terminal of the first clamping diode D A The output end is connected with a third clamping diode D C An input terminal of (1);
second clamping diode D B The filtering and follow current inductance L 1 Is connected in turn to a fifth switching device S A And a sixth switching device S B A second clamping diode D B Said second clamping diode D B The output end is connected with the direct current side photovoltaic panel;
a capacitor C having one end connected to the first clamping diode D A Is connected to the other end of the capacitor C is connected to the fifth switching device S A And a sixth switching device S B To (c) to (d);
first switching device S 1 One end of which is connected with the third clamping diode D C Is connected with the output end of the first switch, and the other end of the first switch is connected with a third switch S 3 Device, the third switching device S 3 The direct current side photovoltaic panel is connected with the direct current side photovoltaic panel;
second switching device S 2 One end of which is connected with the third clamping diode D C Is connected to the output terminal of the first switching device, and the other end is connected to a fourth switching device S 4 Said fourth switching device S 4 The photovoltaic panel is connected with the direct current side photovoltaic panel;
one end of the grid-connected AC side is connected to the first switching device S 1 And the third switching device S 3 The other end of the grid-connected AC side is connected to the second switching device S 2 And said fourth switching device S 4 Said first switching device S 1 A second switching device S 2 A third switching device S 3 And a fourth switching device S 4 The photovoltaic grid-connected inverter is used for inverting the direct-current voltage of the photovoltaic panel on the direct-current side into the alternating-current voltage which can be received on the grid-connected alternating-current side.
Optionally, an open-loop control method for a single-phase three-level micro photovoltaic inverter includes:
s1, acquiring a capacitor voltage reference value v according to frequency requirements of a grid-connected alternating current side c ref And a reference value of the capacitance current i c ref ；
S2, obtaining a grid-connected AC side current reference value i according to the power generated by the DC side photovoltaic panel and the reference voltage amplitude of the grid-connected AC side ac ref ；
S3, according to the capacitance current reference value i c ref And a grid-connected AC side current reference value i ac ref Obtaining a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ；
S4, according to the grid-connected AC side voltage reference value v ac ref Positive and negative judgment third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 In combination with a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Obtaining a first switching signal GS 1 Second switching signal GS 2 The fifth switching signal GS A And a sixth switching signal GS B To control the first switching devices S respectively 1 A second switching device S 2 A fifth switching device S A And a sixth switching device S B ；
And S5, sending all the switching signals to corresponding switching devices of the inverter to drive the inverter.
Optionally, in the step S1,
grid-connected AC side voltage reference value v ac ref And a grid-connected AC side current reference value i ac ref According to formula (1):
instantaneous power P at grid-connected AC side ac As shown in the formula (2),
pulsating power P at double line frequency r The reference value v of the capacitor voltage can be obtained by the complete buffering of the capacitor C c ref And a reference value of the capacitance current i c ref ：
Wherein, V ac Representing the amplitude, I, of the reference voltage on the grid-connection AC side ac Representing the amplitude of the reference current at the grid-connected alternating current side; v c Represents the average value of the capacitor voltage, is a design variable and needs to satisfy V c >P dc /ωC b * sin (2 ω t); ω =2 π f represents the electrical angular velocity on the grid-connected AC side, and f represents the voltage frequency on the grid-connected AC side; c b Representing capacitance value of the capacitor; p is dc Representing the generated power of the photovoltaic panel.
Optionally, in the step S2,
generated power P according to photovoltaic panel dc And obtaining a grid-connected alternating current side current reference value i by combining the formula (1) and the formula (3) ac ref ：
Optionally, in the step S3,
the conduction duty ratios of four working states of the single-phase three-level micro photovoltaic inverter are respectively d 1 、d 2 、d 3 And d 4 Wherein d is 1 +d 2 +d 3 +d 4 =1, fifth switching device S in state 1 A And a sixth switching device S B On, fifth switching device S in State 2 A And a sixth switching device S B Off, fifth switching device S in state 3 A Open and sixth switching device S B Off, fifth switching device S in state 4 A Off and sixth switching device S B On, fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Expressed as formula (7):
one switching period T according to equation (8) s Internal grid-connected AC side current reference value i ac ref DC input current I dc And a capacitive reference current i c ref To obtain the fifth switching device S shown in formula (9) A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ：
Wherein, V dc Generating power for DC side photovoltaic panelThe voltage of (b) can be measured by a voltage sensor.
Optionally, in the step S4,
a fifth switching device S obtained by the formula (9) A On duty cycle d of A And a sixth switching device S B On duty cycle d of B And period of T s Amplitude of 1 triangular carrier wave W ave Comparing to obtain a fifth switching signal GS according to the formula (10) A And a sixth switching signal GS B ：
Grid-connected AC side voltage reference value v obtained according to formula (1) ac ref And the third switching device S is obtained by the formula (11) 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 ：
The fifth switching signal GS obtained according to the formula (10) and the formula (11) A The sixth switching signal GS B And a third switching signal GS 3 And a fourth switching signal GS 4 Obtaining a first switching signal GS 1 And a second switching signal GS 2 ：
Where 0 denotes turning off the switching device and 1 denotes activating the switching device.
Optionally, a system of the open-loop control method for the single-phase three-level micro photovoltaic inverter includes:
a capacitor voltage reference value acquisition module for acquiring a capacitor voltage reference value v c ref ；
Reference value of capacitance and currentA module for obtaining a reference value i of the capacitance current c ref ；
The grid-connected AC side reference current acquisition module receives the information of the capacitance voltage reference value acquisition module, and is used for acquiring a grid-connected AC side current reference value i ac ref ；
A switch on ratio obtaining module for receiving the information of the capacitance voltage reference value obtaining module, the capacitance current reference value obtaining module and the grid-connected AC side reference current obtaining module and obtaining a fifth switch device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ；
An inverter bridge switching signal module for obtaining a third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 ；
A switching signal acquisition module for acquiring the first switching device S 1 First switching signal GS of 1 A second switching device S 2 Second switching signal GS 2 And a fifth switching device S A Of the fifth switching signal GS A And a sixth switching device S B Sixth switching signal GS of B ；
And the output module is used for sending each switching signal to the corresponding switching device of the inverter so as to drive the inverter.
Compared with the prior art, the invention has the following advantages:
in the single-phase three-level micro photovoltaic inverter and the open-loop control method and system thereof, the inverter consists of a filtering and follow-up current inductor, a capacitor, a plurality of clamping diodes and a switching device, and can well invert the direct current voltage of a photovoltaic panel at the direct current side into the alternating current voltage which can be received at the grid-connected alternating current side.
Furthermore, in the open-loop control method of the inverter, firstly, a reference value v of the capacitor voltage is obtained c ref And a reference value of the capacitance current i c ref (ii) a Secondly, the power P generated according to the photovoltaic panel dc And exchangeReference voltage amplitude V ac Obtaining a grid-connected AC side current reference value i ac ref (ii) a Then, the capacitance current is referenced to the value i c ref And a grid-connected AC side current reference value i ac ref The sending switch conducting ratio obtaining module obtains a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B . Then according to the reference value v of the grid-connected AC side voltage ac ref To obtain a third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 In combination with a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Obtaining a first switching signal GS 1 Second switching signal GS 2 The fifth switching signal GS A And a sixth switching signal GS B . Finally, all the switching signals are sent to the corresponding switching devices to drive the inverter. The open-loop control method simply and effectively enables the inverter to realize the inversion control of the direct current of the photovoltaic panel, and outputs the alternating voltage and current with higher sine degree and lower harmonic content which can meet the grid-connected requirement.
Drawings
FIG. 1 is a schematic diagram of the open-loop control principle of a single-phase three-level micro photovoltaic inverter according to the present invention;
fig. 2 (a) is a partial schematic diagram of a single-phase three-level micro photovoltaic inverter of the present invention in state 1;
FIG. 2 (b) is a partial schematic view of a single-phase three-level micro photovoltaic inverter of the present invention in state 2;
FIG. 2 (c) is a partial schematic diagram of a single-phase three-level micro photovoltaic inverter of the present invention in state 3;
FIG. 2 (d) is a partial schematic diagram of a single-phase three-level micro photovoltaic inverter of the present invention in state 4;
FIG. 3 is a schematic flow chart of an open-loop control method for a single-phase three-level micro photovoltaic inverter according to the present invention;
FIG. 4 is a simulation result of the output current of the single-phase three-level micro photovoltaic inverter of the present invention;
fig. 5 is a simulation result of the output voltage of the single-phase three-level micro photovoltaic inverter of the present invention.
Detailed Description
The present invention will be further described by the following detailed description of a preferred embodiment thereof, which is to be read in connection with the accompanying drawings.
As shown in fig. 1, a schematic diagram of an open-loop control principle of a single-phase three-level micro-pv inverter 7 according to the present invention is shown, wherein the single-phase three-level micro-pv inverter 7 (may be simply referred to as an inverter) comprises: filtering and follow current inductance L 1 A first clamping diode D A A second clamping diode D B A third clamping diode D C Capacitor C, first switching device S 1 A second switching device S 2 A third switching device S 3 And a fourth switching device S 4 A fifth switching device S A And a sixth switching device S B 。
Wherein, U dc And the direct-current voltage generated by the photovoltaic panel is used for outputting power to the grid-connected alternating-current side. The filtering and follow current inductance L 1 The input end is connected with a DC side photovoltaic panel, and the filtering and follow current inductance L 1 The method is used for keeping the output current of the photovoltaic panel on the direct current side stable and reducing current ripples. The first clamping diode D A Input terminal and the filtering and follow current inductance L 1 Is connected to the output terminal of the first clamping diode D A The output end is connected with a third clamping diode D C To the input terminal of (1). The filtering and follow current inductance L 1 Is connected in turn to a fifth switching device S A And a sixth switching device S B A second clamping diode D B Said second clamping diode D B The output end is connected with the DC side photovoltaic panel. One end of the capacitor C and the first clamping diode D A Is connected to the other end of the capacitor C is connected to the fifth switching device S A And a sixth switching device S B In between. The first mentionedA clamping diode D A A second clamping diode D B A third clamping diode D C The capacitor C is used for preventing current from flowing back to a direct current side from the capacitor C and a grid-connected alternating current side.
The first switching device S 1 One end of the third clamping diode D C Is connected with the output end of the first switch and is connected with a third switch S at the other end 3 Device, the third switching device S 3 And the photovoltaic panel is connected with the direct current side photovoltaic panel. The second switching device S 2 One end of the third clamping diode D C Is connected to the output terminal of the first switching device, and the other end of the first switching device is connected to a fourth switching device S 4 Said fourth switching device S 4 And the photovoltaic panel is connected with the direct current side photovoltaic panel. One end of the grid-connected AC side is connected to the first switching device S 1 And the third switching device S 3 The other end of the grid-connected AC side is connected to the second switching device S 2 And said fourth switching device S 4 Said first switching device S 1 A second switching device S 2 A third switching device S 3 And a fourth switching device S 4 The photovoltaic grid-connected inverter is used for inverting the direct-current voltage of the photovoltaic panel on the direct-current side into the alternating-current voltage which can be received on the grid-connected alternating-current side.
Wherein the fifth switching device S A And a sixth switching device S B For realizing 4 operating states of the inverter 7. As shown in fig. 2 (a), when the inverter 7 is in the state 1, the fifth switching device S A And a sixth switching device S B And (4) opening. As shown in fig. 2 (b), when the inverter 7 is in the state 2, the fifth switching device S A And a sixth switching device S B And (6) turning off. As shown in fig. 2 (c), when the inverter 7 is in the state 3, the fifth switching device S A Open and sixth switching device S B And (6) turning off. As shown in fig. 2 (d), when the inverter 7 is in the state 4, the fifth switching device S A Off and sixth switching device S B And (4) opening.
In this embodiment, the capacitor C is a dual-frequency power compensation capacitor, and can divide the voltage output to the grid-connected ac side into three levels, which are respectively the 0 level in the state 1 and the state 4, and the U in the state 2 dc Level of electricityAnd U of state 3 dc +v c Level (v) c The voltage across the capacitor C).
Further, as shown in fig. 3, the invention also discloses an open-loop control method of the single-phase three-level micro photovoltaic inverter 7 (i.e. an open-loop control algorithm of the inverter 7), wherein the amplitude V of the reference voltage on the grid-connected ac side ac Frequency f, generated power P of photovoltaic panel dc Period T s Average value of capacitor voltage V c Known from existing information.
Specifically, the open-loop control method includes:
s1, acquiring a capacitor voltage reference value v according to frequency requirements of a grid-connected alternating current side c ref And obtaining a reference value i of the capacitor current according to the relation between the voltage and the current at the two ends of the capacitor C c ref 。
In the step S1, a grid-connected AC side voltage reference value v ac ref And a grid-connected AC side current reference value i ac ref According to formula (1):
instantaneous power P at grid-connected AC side ac As shown in the formula (2),
pulsating power P at double line frequency r The reference value v of the capacitor voltage can be obtained by completely buffering by the capacitor C c ref And a reference value of the capacitance current i c ref ：
Wherein, V ac Representing the amplitude, I, of the reference voltage on the grid-connection AC side ac Representing the amplitude of the reference current of the grid-connected alternating current side; v c Represents the average value of the capacitor voltage, is a design variable and needs to satisfy V c >P dc /ωC b * sin (2 ω t); ω =2 π f represents the electrical angular velocity on the grid-connected AC side, and f represents the voltage frequency on the grid-connected AC side; c b Representing capacitance value of the capacitor; p is dc The generated power of the photovoltaic panel is represented as a given value in the open-loop control method of the present invention.
S2, acquiring a grid-connected alternating current side current reference value i according to the power generated by the photovoltaic panel on the direct current side and the reference voltage amplitude on the grid-connected alternating current side ac ref 。
In the step S2, the generated power P of the photovoltaic panel is used as the basis dc And obtaining a grid-connected alternating current side current reference value i by combining the formula (1) and the formula (3) ac ref ：
S3, according to the capacitance current reference value i c ref And a grid-connected AC side current reference value i ac ref Obtaining a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B 。
In the step S3, the conduction duty ratios of the four working states of the single-phase three-level micro photovoltaic inverter 7 are d respectively 1 、d 2 、d 3 And d 4 (corresponding to State 1, state 2, state 3, and State 4, respectively), where d 1 +d 2 +d 3 +d 4 =1, fifth switching device S in state 1 A And a sixth switching device S B On, in state 2Five switching devices S A And a sixth switching device S B Off, fifth switching device S in state 3 A Open and sixth switching device S B Off, fifth switching device S in state 4 A Off and sixth switching device S B On, fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Can be expressed as formula (7):
one switching period T according to equation (8) s Internal grid-connected AC side current reference value i ac ref DC input current I dc And a capacitive reference current i c ref To obtain the fifth switching device S shown in formula (9) A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ：
Wherein, V dc The voltage generated by the photovoltaic panel on the direct current side can be measured by a voltage sensor.
S4, according to the grid-connected AC side voltage reference value v ac ref Positive and negative judgment third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 In combination with a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Obtaining a first switching signal GS 1 Second switching signal GS 2 The fifth switching signal GS A And a sixth switch signalNumber GS B To control the first switching devices S respectively 1 A second switching device S 2 A fifth switching device S A And a sixth switching device S B 。
Specifically, in the step S4, the fifth switching device S obtained by the formula (9) is used A On duty cycle d of A And a sixth switching device S B On duty cycle d of B And period of T s Amplitude of 1 triangular carrier wave W ave Comparing to obtain a fifth switching signal GS according to the formula (10) A And a sixth switching signal GS B ：
Obtaining a grid-connected AC side voltage reference value v according to a formula (1) ac ref And the third switching device S is obtained by the formula (11) 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 ：
The fifth switching signal GS obtained according to the formula (10) and the formula (11) A The sixth switching signal GS B And a third switching signal GS 3 And the fourth switching signal GS 4 Obtaining a first switching signal GS 1 And a second switching signal GS 2 ：
Where 0 denotes turning off the switching device and 1 denotes activating the switching device.
And S5, sending all the switching signals to corresponding switching devices of the inverter 7 to drive the inverter 7.
Based on the same inventive concept, as shown in fig. 1, the invention also discloses a system of the open-loop control method for the single-phase three-level micro photovoltaic inverter 7, which comprises: the device comprises a capacitance voltage reference value acquisition module 1, a capacitance current reference value acquisition module 2, a grid-connected alternating current side reference current acquisition module 3, a switch conduction ratio acquisition module 5, an inverter bridge switch signal module 4, a switch signal acquisition module 6 and an output module.
The capacitance voltage reference value obtaining module 1 is used for obtaining a capacitance voltage reference value v c ref The capacitance current reference value obtaining module 2 is used for obtaining a capacitance current reference value i c ref The grid-connected alternating current side reference current acquisition module 3 receives the information of the capacitance voltage reference value acquisition module 1, and the grid-connected alternating current side reference current acquisition module 3 is used for acquiring a grid-connected alternating current side current reference value i ac ref . The switch on ratio obtaining module 5 receives the information of the capacitance voltage reference value obtaining module 1, the capacitance current reference value obtaining module 2 and the grid-connected alternating current side reference current obtaining module 3, and obtains a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B . The inverter bridge switching signal module 4 is used for obtaining a third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 . The switching signal acquisition module 6 is used for acquiring a first switching device S 1 First switching signal GS of 1 A second switching device S 2 Second switching signal GS 2 A fifth switching device S A Of the fifth switching signal GS A And a sixth switching device S B Sixth switching signal GS of B . The output module (not shown in the figure) is used for sending each switching signal to the corresponding switching device of the inverter 7 to drive the inverter 7.
In one embodiment, the signal generated by the open-loop control method and system for the single-phase three-level micro photovoltaic inverter 7 of the invention is used for controlling the inverter 7 to output a current simulation result. As shown in fig. 4, it can be seen that, based on the above control method and system, the photovoltaic inverter 7 can obtain an output current with low harmonic content and high sine degree. As shown in the figure5, the simulation result of the output voltage of the inverter 7 shows that the output voltage v on the grid-connected AC side ac Can also maintain higher sine degree and accurately track the voltage reference value v at the grid-connected AC side ac ref A change in (c).
In summary, in the single-phase three-level micro photovoltaic inverter 7, the open-loop control method and the system of the present invention, the inverter 7 is composed of a filtering and follow-up inductor L 1 The capacitor C, the clamping diodes and the switching device can invert the direct-current voltage of the photovoltaic panel at the direct-current side into alternating-current voltage meeting grid-connected requirements, and grid-connected control of electric energy is achieved. In the open-loop control method of the inverter 7, a capacitor voltage reference value v is firstly obtained c ref And a reference value of the capacitance current i c ref (ii) a Secondly, according to the power P generated by the photovoltaic panel dc And an AC reference voltage amplitude V ac Obtaining a grid-connected AC side current reference value i ac ref (ii) a Then, the capacitance current is referenced to the value i c ref And a grid-connected AC side current reference value i ac ref The sending-in switch conduction ratio obtaining module 5 obtains a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B . Then according to the reference value v of the grid-connected AC side voltage ac ref To obtain a third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 In combination with a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Obtaining a first switching signal GS 1 Second switching signal GS 2 The fifth switching signal GS A And a sixth switching signal GS B . Finally, all the switching signals are sent to the corresponding switching devices to drive the inverter 7. The open-loop control method simply and effectively enables the inverter 7 to realize the inversion control of the direct current of the photovoltaic panel, outputs the sine alternating current which can meet the grid-connected requirement, has simple steps, is easy to realize, and is suitable for large-scale popularization and application.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.
Claims (7)
1. A single-phase three-level micro photovoltaic inverter, comprising:
filtering and follow current inductance L 1 The input end of the filter is connected with one end of the DC side photovoltaic panel, and the filter and follow current inductor L 1 The photovoltaic power generation device is used for keeping the output current of the photovoltaic panel on the direct current side stable and reducing current ripples;
first clamping diode D A Its input terminal and the filtering and follow current inductance L 1 Is connected to the output terminal of the first clamping diode D A The output end is connected with a third clamping diode D C An input terminal of (1);
second clamping diode D B The filtering and follow current inductance L 1 Is sequentially connected with a fifth switching device S A And a sixth switching device S B A second clamping diode D B Said second clamping diode D B The output end is connected with the other end of the direct current side photovoltaic panel;
a capacitor C having one end connected to the first clamping diode D A Is connected to the other end of the capacitor C is connected to the fifth switching device S A And a sixth switching device S B To (c) to (d);
first switching device S 1 One end of which is connected with the third clamping diode D C Is connected with the output end of the first switch device and the other end is connected with a third switch device S 3 One terminal, the third switching device S 3 The other end of the photovoltaic module is connected with the direct current side photovoltaic panel;
second switching device S 2 One end of which is connected with the third clamping diode D C Is connected to the output terminal of the first switching device, and the other end is connected to a fourth switching device S 4 One end, the fourth switching device S 4 The other end of the photovoltaic module is connected with the other end of the direct current side photovoltaic panel;
one end of the grid-connected AC side is connected to the first switching device S 1 And said third switching device S 3 The other end of the grid-connected AC side is connected to the second switching device S 2 And said fourth switching device S 4 Said first switching device S 1 A second switching device S 2 A third switching device S 3 And a fourth switching device S 4 The inverter is used for inverting the direct-current voltage of the photovoltaic panel on the direct-current side into the alternating-current voltage which can be received on the grid-connected alternating-current side.
2. The open-loop control method of the single-phase three-level micro pv inverter of claim 1, comprising:
s1, acquiring a capacitor voltage reference value v according to frequency requirements of a grid-connected alternating current side c ref And a reference value of the capacitance current i c ref ；
S2, acquiring a grid-connected alternating current side current reference value i according to the power generated by the photovoltaic panel on the direct current side and the reference voltage amplitude on the grid-connected alternating current side ac ref ；
S3, according to the capacitance current reference value i c ref And a grid-connected AC side current reference value i ac ref Obtaining a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ；
S4, according to the grid-connected AC side voltage reference value v ac ref Positive and negative judgment third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 In combination with a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Obtaining a first switching signal GS 1 Second switching signal GS 2 The fifth switching signal GS A And a sixth switching signal GS B To control the first switching devices S respectively 1 A second switching device S 2 And a fifth switching device S A And a sixth switching device S B ；
And S5, sending all the switching signals to corresponding switching devices of the inverter to drive the inverter.
3. The open-loop control method of a single-phase three-level micro photovoltaic inverter according to claim 2, wherein in step S1,
grid-connected AC side voltage reference value v ac ref And a grid-connected AC side current reference value i ac ref According to formula (1):
instantaneous power P at grid-connected AC side ac As shown in the formula (2), the first,
pulsating power P at double line frequency r The reference value v of the capacitor voltage can be obtained by completely buffering by the capacitor C c ref And a reference value of the capacitance current i c ref ：
Wherein, V ac Representing grid-connected ac-side reference voltagesAmplitude, I ac Representing the amplitude of the reference current of the grid-connected alternating current side; v c Represents the average value of the capacitor voltage, is a design variable and needs to satisfy V c >P dc /ωC b * sin (2 ω t); ω =2 π f represents the electrical angular velocity on the grid-connected AC side, and f represents the voltage frequency on the grid-connected AC side; c b Representing capacitance value of the capacitor; p dc Representing the generated power of the photovoltaic panel.
4. The open-loop control method of a single-phase three-level micro photovoltaic inverter according to claim 3, wherein in the step S2,
generated power P according to photovoltaic panel dc And obtaining a grid-connected alternating current side current reference value i by combining the formula (1) and the formula (3) ac ref ：
5. The open-loop control method of a single-phase three-level micro photovoltaic inverter according to claim 4, wherein in the step S3,
the conduction duty ratios of four working states of the single-phase three-level micro photovoltaic inverter are respectively d 1 、d 2 、d 3 And d 4 Wherein d is 1 +d 2 +d 3 +d 4 =1, fifth switching device S in state 1 A And a sixth switching device S B On, fifth switching device S in State 2 A And a sixth switching device S B Off, fifth switching device S in state 3 A Open and sixth switching device S B Off, fifth switching device S in state 4 A Off and sixth switching device S B On, fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B Expressed as formula (7):
one switching period T according to equation (8) s Internal grid-connected AC side current reference value i ac ref DC input current I dc And a capacitive reference current i c ref To obtain the fifth switching device S shown in formula (9) A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ：
Wherein, V dc The voltage generated by the photovoltaic panel on the direct current side can be measured by a voltage sensor.
6. The open-loop control method of a single-phase three-level micro photovoltaic inverter according to claim 5, wherein in step S4,
a fifth switching device S obtained by the formula (9) A On duty cycle d of A And a sixth switching device S B On duty cycle d of B And period of T s Amplitude of 1 triangular carrier wave W ave Comparing to obtain a fifth switching signal GS according to the formula (10) A And a sixth switching signal GS B ：
Obtaining a grid-connected AC side voltage reference value v according to a formula (1) ac ref And the third switching device S is obtained by the formula (11) 3 Third switching signal GS 3 And a fourth switchDevice S 4 Of the fourth switching signal GS 4 ：
The fifth switching signal GS obtained according to the formula (10) and the formula (11) A The sixth switching signal GS B And a third switching signal GS 3 And the fourth switching signal GS 4 Obtaining a first switching signal GS 1 And a second switching signal GS 2 ：
Where 0 denotes turning off the switching device and 1 denotes activating the switching device.
7. A system for the open-loop control method of a single-phase three-level micro PV inverter according to any of claims 2 to 6, comprising:
a capacitor voltage reference value acquisition module for acquiring a capacitor voltage reference value v c ref ；
A capacitance current reference value obtaining module for obtaining a capacitance current reference value i c ref ；
The grid-connected AC side reference current acquisition module receives the information of the capacitance voltage reference value acquisition module, and is used for acquiring a grid-connected AC side current reference value i ac ref ；
A switch on ratio acquisition module for receiving the information of the capacitance current reference value acquisition module and the grid-connected AC side reference current acquisition module and acquiring a fifth switching device S A On duty cycle d of A And a sixth switching device S B On duty cycle d of B ；
An inverter bridge switching signal module for obtaining a third switching device S 3 Third switching signal GS 3 And a fourth switching device S 4 Of the fourth switching signal GS 4 ；
A switching signal acquisition module for acquiring the first switching device S 1 First switching signal GS of 1 A second switching device S 2 Second switching signal GS 2 A fifth switching device S A Of the fifth switching signal GS A And a sixth switching device S B Sixth switching signal GS of B ；
And the output module is used for sending each switching signal to the corresponding switching device of the inverter so as to drive the inverter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011247021.5A CN112398360B (en) | 2020-11-10 | 2020-11-10 | Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011247021.5A CN112398360B (en) | 2020-11-10 | 2020-11-10 | Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112398360A CN112398360A (en) | 2021-02-23 |
| CN112398360B true CN112398360B (en) | 2023-04-11 |
Family
ID=74600974
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011247021.5A Active CN112398360B (en) | 2020-11-10 | 2020-11-10 | Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112398360B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113497571A (en) * | 2021-07-05 | 2021-10-12 | 国网上海市电力公司 | Grid-connected micro inverter, control method and control system |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012119451A1 (en) * | 2011-03-10 | 2012-09-13 | 浙江大学 | Single-phase three-level inverter |
| CN103248256A (en) * | 2013-05-20 | 2013-08-14 | 合肥工业大学 | Voltage-multiplying three-level photovoltaic grid-connected inverter with neutral point balance capability |
| CN203691279U (en) * | 2013-12-17 | 2014-07-02 | 哈尔滨九洲电气股份有限公司 | Topologically structured circuit of mini photovoltaic inverter |
| US10038393B1 (en) * | 2017-11-02 | 2018-07-31 | National Chung-Shan Institute Of Science & Technology | Single-phase non-isolated inverter |
| WO2020068022A2 (en) * | 2018-09-29 | 2020-04-02 | Dokuz Eylül Üni̇versi̇tesi̇ Rektörlüğü | A single phase inverter for photovoltaic panels |
| WO2020108759A1 (en) * | 2018-11-29 | 2020-06-04 | Siemens Aktiengesellschaft | Micro solar inverter |
-
2020
- 2020-11-10 CN CN202011247021.5A patent/CN112398360B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012119451A1 (en) * | 2011-03-10 | 2012-09-13 | 浙江大学 | Single-phase three-level inverter |
| CN103248256A (en) * | 2013-05-20 | 2013-08-14 | 合肥工业大学 | Voltage-multiplying three-level photovoltaic grid-connected inverter with neutral point balance capability |
| CN203691279U (en) * | 2013-12-17 | 2014-07-02 | 哈尔滨九洲电气股份有限公司 | Topologically structured circuit of mini photovoltaic inverter |
| US10038393B1 (en) * | 2017-11-02 | 2018-07-31 | National Chung-Shan Institute Of Science & Technology | Single-phase non-isolated inverter |
| WO2020068022A2 (en) * | 2018-09-29 | 2020-04-02 | Dokuz Eylül Üni̇versi̇tesi̇ Rektörlüğü | A single phase inverter for photovoltaic panels |
| WO2020108759A1 (en) * | 2018-11-29 | 2020-06-04 | Siemens Aktiengesellschaft | Micro solar inverter |
Non-Patent Citations (1)
| Title |
|---|
| 非隔离光伏并网逆变技术的现状与展望;肖华锋 等;《中国电机工程学报》;20200220;第40卷(第04期);第1038-1054页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112398360A (en) | 2021-02-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8111528B2 (en) | DC to AC inverter | |
| CN107210684A (en) | Five level topology units and five-electrical level inverter | |
| CN104638971A (en) | Photovoltaic grid-connected inverter and control method thereof | |
| Patil et al. | Designing Of Z-source inverter for photovoltaic system using MATLAB/SIMULINK | |
| CN108141147A (en) | The five-electrical level inverter topological circuit of high voltage gain | |
| CN112398360B (en) | Single-phase three-level micro photovoltaic inverter and open-loop control method and system thereof | |
| CN113193755B (en) | Multi-port converter based on topology integration, control method and system | |
| CN202435291U (en) | PFC (Power Factor Correction) boost circuit with adjustable carrier wave amplitude | |
| CN109873559A (en) | The double BUCK-BOOST bucks of modularization export the combined inverter of inverse parallel | |
| Adle et al. | Photovoltaic based series z-source inverter fed induction motor drive with improved shoot through technique | |
| Sudiharto et al. | Design and implementation unipolar SPWM full-bridge inverter using fuzzy Sugeno in DC microgrid isolated system | |
| Kim et al. | A new multilevel inverter with reduced switch count for renewable power applications | |
| Yang et al. | A novel single-phase transformerless photovoltaic inveter connected to grid | |
| CN102118035B (en) | Grid-connected inverter | |
| Mohammad et al. | Design and evaluation of solar inverter for different power factor loads | |
| CN107508479B (en) | Four-switch alternating-current side power decoupling circuit and decoupling control method | |
| Razi et al. | A novel single-stage PWM microinverter topology using two-power switches | |
| Vijayaraja et al. | An investigation and design of symmetric and asymmetric inverter for various applications | |
| CN111934578A (en) | Dual-mode photovoltaic inverter circuit system based on hybrid control | |
| Colak et al. | Conventional H-bridge and recent multilevel inverter topologies | |
| CN111277160A (en) | Six-switch power decoupling circuit and control method thereof | |
| CN210867533U (en) | Six-switch power decoupling circuit | |
| CN217307549U (en) | Coupling inductance type double-Boost inverter | |
| Razi et al. | Comparative performance analysis of bipolar and unipolar pseudo-based inverter for off-grid photovoltaic application | |
| CN104578882B (en) | Voltage type Tran-z-source miniature inverter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |