CN111490717A - Photovoltaic power generation system with isolated photovoltaic optimizer - Google Patents
Photovoltaic power generation system with isolated photovoltaic optimizer Download PDFInfo
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- CN111490717A CN111490717A CN202010431559.5A CN202010431559A CN111490717A CN 111490717 A CN111490717 A CN 111490717A CN 202010431559 A CN202010431559 A CN 202010431559A CN 111490717 A CN111490717 A CN 111490717A
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- 238000010248 power generation Methods 0.000 title claims abstract description 22
- 230000001360 synchronised effect Effects 0.000 claims description 9
- 239000003990 capacitor Substances 0.000 claims description 8
- 238000002955 isolation Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 7
- 230000000712 assembly Effects 0.000 description 4
- 238000000429 assembly Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S10/00—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/66—Regulating electric power
- G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
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- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc 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
- H02M7/217—Conversion of ac power input into dc 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
- H02M7/219—Conversion of ac power input into dc 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 in a bridge configuration
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/30—Electrical components
- H02S40/34—Electrical components comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
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- 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
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
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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
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a photovoltaic power generation system with an isolated photovoltaic optimizer, which belongs to the technical field of photovoltaic power generation.A plurality of photovoltaic components are connected in series to form a photovoltaic subgroup string and then connected with the isolated photovoltaic optimizer, and all the isolated photovoltaic optimizers are connected in series and then connected with a photovoltaic inverter.
Description
Technical Field
The invention belongs to the technical field of photovoltaic power generation, and particularly relates to a photovoltaic power generation system with an isolated photovoltaic optimizer.
Background
The DC voltage level of the photovoltaic system is improved, so that the line loss is reduced, and the system cost is reduced. The conventional photovoltaic system can obtain a larger direct current voltage grade, such as 1000V or 1500V direct current voltage, by connecting the modules in series, but the photovoltaic modules in the string are required to have the insulation voltage resistance level of 1000V or 1500V simultaneously while obtaining 1000V direct current voltage and 1500V direct current voltage. Because no photovoltaic module with voltage-resistant grade above 1500V exists at present, and no related technical standard exists, the photovoltaic system is limited to be developed to a higher direct-current voltage grade.
Meanwhile, under the condition that the withstand voltage grade of the photovoltaic module meets the high-voltage requirement, obtaining better direct-current bus voltage means that more photovoltaic modules are required to be connected in series, and more series connection means higher series mismatch probability, so that improvement of system electric quantity is not facilitated.
Disclosure of Invention
In order to solve the existing problems, the invention aims to provide a photovoltaic power generation system with an isolated photovoltaic optimizer, which realizes complete electrical isolation of an input side and an output side of the photovoltaic optimizer, realizes a higher direct-current voltage grade under the condition of not improving the voltage-resistant grade of a photovoltaic assembly, avoids the risk of series mismatch caused by long strings, improves the efficiency of the photovoltaic system, and obviously reduces the system cost.
The invention is realized by the following technical scheme:
the invention discloses a photovoltaic power generation system with isolated photovoltaic optimizers, wherein a plurality of photovoltaic modules are connected in series to form a photovoltaic subgroup string, each photovoltaic subgroup string is connected with one isolated photovoltaic optimizer, and all the isolated photovoltaic optimizers are connected in series and then connected with a photovoltaic inverter;
the isolated photovoltaic optimizer comprises a full-bridge LL C circuit consisting of an input side current-voltage sensor, an H-bridge, a resonant capacitor, a high-frequency transformer, a synchronous rectification circuit and an output side current-voltage sensor which are sequentially connected from the input side to the output side, wherein the H-bridge is connected with a control and drive module, the control and drive module is also respectively connected with the input side current-voltage sensor and the output side current-voltage sensor, and a photoelectric coupler is connected between the control and drive module and the output side current-voltage sensor.
Preferably, the H bridge comprises 4 switching tubes, the 4 switching tubes are connected in series in pairs, and the two serial branches are connected through a central point; the two series branches are connected with an input power supply, and the central point is connected with the resonant capacitor.
Further preferably, the switch tube is a GaN switch tube, a SiC switch tube or a Si switch tube.
Preferably, the control and drive module comprises an MCU and a drive circuit, the MCU is connected to the drive circuit, the drive circuit is connected to the H-bridge, and the MCU is connected to the input side current-voltage sensor and the photocoupler, respectively.
Preferably, the high frequency transformer is a center tapped transformer.
Preferably, the synchronous rectification circuit comprises a half-bridge rectification circuit formed by two mosfet tubes.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention discloses a photovoltaic power generation system with an isolation type photovoltaic optimizer, wherein a full bridge LL C circuit is used for realizing the MPPT function of an accessed photovoltaic component or a group string, an isolation circuit formed by a high-frequency transformer and a photoelectric coupler is used for power isolation and signal isolation, the complete electrical isolation of the input side and the output side of the photovoltaic optimizer is realized, a control and drive module is used for controlling the running states of a full bridge LL C circuit and the isolation circuit, the photovoltaic components in the photovoltaic power generation system are not directly connected in series to form the group string, but a plurality of photovoltaic components are connected in series to form a photovoltaic group string, each photovoltaic group string is connected into the isolation type photovoltaic optimizer, the isolation type photovoltaic optimizers are connected in series to form a higher-voltage photovoltaic group string, and the photovoltaic group string is connected into an inverter to perform grid-connected power generation.
Further, the inverter conversion from direct current to alternating current can be realized through the switching control of the H-bridge switching tube, the output can be kept constant when the load and the input are changed by controlling the switching frequency of the H-bridge switching tube, the switching of the switching tube in the full load range to Zero Voltage Switching (ZVS) can be realized, and the high efficiency is realized.
Furthermore, the switch tube adopts a GaN switch tube, a SiC switch tube or a Si switch tube, so that the switch tube has high switching frequency, low loss and high reliability.
Furthermore, the MCU collects input voltage and current through an input side current-voltage sensor, collects output voltage and current through a photoelectric coupler, controls the switching frequency of the H bridge through a driving circuit, and realizes PID automatic regulation through software so as to realize the Maximum Power Point Tracking (MPPT) function.
Further, the high frequency transformer is a transformer with a center tap, which facilitates full-wave rectification.
Furthermore, the synchronous rectification circuit comprises a half-bridge rectification circuit consisting of two mosfet tubes, and a synchronous rectification mode is adopted, so that rectification loss can be reduced, and circuit efficiency is improved
Drawings
FIG. 1 is a simplified functional block diagram of an isolated photovoltaic optimizer of the present invention;
FIG. 2 is a schematic circuit diagram of the isolated photovoltaic optimizer of the present invention;
FIG. 3 is a schematic diagram of a system configuration of a photovoltaic power generation system having an isolated photovoltaic optimizer in accordance with the present invention;
fig. 4 is a schematic diagram of another system configuration of the photovoltaic power generation system with the isolated photovoltaic optimizer of the present invention.
In the figure: the photovoltaic module is 1, the isolated photovoltaic optimizer is 2, the input side current and voltage sensor is 21, the H bridge is 22, the resonant capacitor is 23, the high-frequency transformer is 24, the synchronous rectification circuit is 25, the output side current and voltage sensor is 26, the control and drive module is 27, the MCU is 271, the drive circuit is 272, the photoelectric coupler is 28 and the photovoltaic inverter is 3.
Detailed Description
The invention will now be described in further detail with reference to the following drawings and specific examples, which are intended to be illustrative and not limiting:
according to the photovoltaic power generation system with the isolated photovoltaic optimizers, a plurality of photovoltaic modules 1 are connected in series to form photovoltaic subgroup strings, each photovoltaic subgroup string is connected with one isolated photovoltaic optimizer 2, and all the isolated photovoltaic optimizers 2 are connected in series and then connected with a photovoltaic inverter 3.
Referring to fig. 1, an isolated photovoltaic optimizer 2 is composed of three modules, namely, an MPPT (maximum power point tracking) circuit, a control circuit and an isolation circuit, wherein the MPPT circuit is a full-bridge LL C circuit and is used for achieving an MPPT function on an accessed photovoltaic module or a string.
Referring to fig. 2, which is a schematic diagram of a specific circuit of an isolated photovoltaic optimizer, the isolated photovoltaic optimizer 2 includes a full bridge LL C circuit composed of an input side current-voltage sensor 21, an H bridge 22, a resonant capacitor 23, a high-frequency transformer 24, a synchronous rectification circuit 25 and an output side current-voltage sensor 26, which are sequentially connected from the input side to the output side, the H bridge 22 is connected with a control and drive module 27, the control and drive module 27 is further connected with the input side current-voltage sensor 21 and the output side current-voltage sensor 26, a photocoupler 28 is connected between the control and drive module 27 and the output side current-voltage sensor 26, and the synchronous rectification circuit 25 includes a half bridge rectification circuit composed of two mosfets.
The primary side of the high frequency transformer 24 can be equivalent to the leakage inductance L r and the excitation inductance L m and an ideal transformer, so the resonant network formed by the resonant capacitor Cr and the high frequency transformer T has two resonant points, namely
And
the output can be kept constant when the load and the input are changed by controlling the switching frequency of the H-bridge switching tube, and the switching of the switching tube in a full load range to Zero Voltage Switching (ZVS) can be realized, so that the high efficiency is realized. The high frequency transformer 24 is preferably a center tapped transformer.
The H bridge 22 comprises 4 switching tubes, the 4 switching tubes are connected in series in pairs, and two serial branches are connected through a central point; the two series branches are connected with an input power supply, and the central point is connected with a resonant capacitor 23. The switch tube can adopt a GaN switch tube, a SiC switch tube or a Si switch tube.
The control and drive module 27 includes an MCU 271 and a drive circuit 272, the MCU 271 is connected to the drive circuit 272, the drive circuit 272 is connected to the H-bridge 22, and the MCU 271 is connected to the input side current-voltage sensor 21 and the photocoupler 28, respectively.
Referring to fig. 3, a schematic diagram of a system composition of a photovoltaic power generation system with an isolated photovoltaic optimizer according to the present invention is shown, wherein each photovoltaic module 1 is separately connected to an isolated photovoltaic optimizer 2. The isolated photovoltaic optimizers 2 are connected in series to form high voltage, and the high voltage is input to the direct current side of the photovoltaic inverter 3. The isolated photovoltaic optimizer 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. For example, the voltage isolation capability of the input side and the output side is illustrated, for example, the maximum output voltage of each photovoltaic module 1 is 40V, and the maximum output voltage after MPPT tracking by the isolated photovoltaic optimizer 2 is 45V. One photovoltaic sub-group string comprises 50 photovoltaic modules 1, and each photovoltaic module 1 is connected to one isolated photovoltaic optimizer 2 in advance, and 50 isolated photovoltaic optimizers 2 are used in total. After the 50 isolated photovoltaic optimizers 2 are connected in series, the total voltage is increased to 2250V. Assuming that the cathode of the string is grounded, the voltage to ground at the cathode output side of the first isolated photovoltaic optimizer 2 from the cathode is 0V, and the maximum voltage to ground at the anode output side is 45V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground of the input side of the negative electrode of the first isolated photovoltaic optimizer 2 (the output side of the negative electrode of the photovoltaic assembly 1) is 0V, the maximum voltage to ground of the input side of the positive electrode (the output side of the positive electrode of the photovoltaic assembly 1) is 40V, the maximum voltage to ground of the negative electrode of the second isolated photovoltaic optimizer 2 is 40V, and therefore the maximum voltage to ground of the positive electrode is 90V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground on the input side of the cathode of the second isolated photovoltaic optimizer 2 (the output side of the cathode of the photovoltaic assembly 1) is 0V, and the maximum voltage to ground on the input side of the anode (the output side of the anode of the photovoltaic assembly 1) is 40V. By analogy, the maximum voltage of the negative pole of the nth isolated photovoltaic optimizer 2 to the ground is (n-1) × 45V, and the maximum voltage of the positive pole to the ground is n × 45V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground on the input side of the negative electrode of the first isolated photovoltaic optimizer 2 (the output side of the negative electrode of the photovoltaic assembly 1) is 0V, and the maximum voltage to ground on the input side of the positive electrode (the output side of the positive electrode of the photovoltaic assembly 1) is 40V. Therefore, under the system architecture, no matter how many isolated photovoltaic optimizers 2 are connected in series, the voltage to ground on the input side of each isolated photovoltaic optimizer 2 is not accumulated, so that the voltage to withstand of the photovoltaic assembly 1 can be kept lower while a higher set of series direct-current voltages can be realized. Meanwhile, the isolated photovoltaic optimizers 2 have independent maximum power point tracking functions, so that no matter how many photovoltaic assemblies 1 are contained in the string, the current mismatch among the photovoltaic assemblies 1 is eliminated by the isolated photovoltaic optimizers 2, and the problem of series mismatch of long strings is solved.
Referring to fig. 4, which is a schematic diagram of another system composition of the photovoltaic power generation system with the isolated photovoltaic optimizer of the present invention, a plurality of photovoltaic modules 1 are connected in series and then connected to an isolated photovoltaic optimizer 2. The isolated photovoltaic optimizers 2 are connected in series to form higher voltage, and the higher voltage is input to the direct current side of the photovoltaic inverter 3. The isolated photovoltaic optimizer 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. For example, the voltage isolation capability of the input side and the output side is illustrated, for example, the maximum output voltage of each photovoltaic module 1 is 40V, 20 photovoltaic modules 1 are connected in series to form a photovoltaic sub-group string with the maximum output voltage of 800V, and the output voltage is 900V after MPPT tracking by the isolated photovoltaic optimizer 2. 3 are total 20 photovoltaic modules 1, insert 3 isolated photovoltaic optimizer 2 respectively, and three isolated photovoltaic optimizer 2 connect in series and form the group string of 2700V voltage. In this system, assuming that the cathode of the string is grounded, the voltage to ground on the cathode output side of the first isolated photovoltaic optimizer 2 from the cathode is 0V, and the maximum voltage to ground on the anode output side is 900V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground on the input side of the negative electrode (the output side of the negative electrode of the photovoltaic subgroup string) of the first isolated photovoltaic optimizer 2 is 0V, the maximum voltage to ground on the input side of the positive electrode (the output side of the positive electrode of the photovoltaic subgroup string) is 800V, and the maximum voltage withstanding requirement of any photovoltaic module 1 in the photovoltaic subgroup string does not exceed 800V. The maximum voltage to ground of the cathode of the second isolated photovoltaic optimizer 2 is 900V, and the maximum voltage to ground of the anode of the second isolated photovoltaic optimizer 2 is 1800V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground of the input side of the cathode (the output side of the cathode of the photovoltaic subgroup string) of the second isolated photovoltaic optimizer 2 is 0V, the voltage to ground of the input side of the anode (the output side of the anode of the photovoltaic subgroup string) is 800V, and the maximum voltage withstand requirement of any photovoltaic module 1 in the photovoltaic subgroup string does not exceed 800V. By analogy, under the system architecture, no matter how many isolated photovoltaic optimizers 2 are connected in series, the voltage to ground on the input side of each isolated photovoltaic optimizer 2 cannot be accumulated, so that the voltage to ground of a higher group of direct-current voltages can be realized, the voltage-withstanding grade of the photovoltaic assembly 1 connected under each isolated photovoltaic optimizer 2 does not exceed the maximum output voltage of a single photovoltaic assembly 1 by the number of series connection, and the voltage-withstanding requirement of the lower photovoltaic assembly 1 is kept. Meanwhile, the isolated photovoltaic optimizers 2 have independent maximum power point tracking functions, so that no matter how many photovoltaic assemblies 1 are contained in the string, the current mismatch among the photovoltaic assemblies 1 is eliminated by the isolated photovoltaic optimizers 2, and the problem of series mismatch of long strings is solved.
It should be noted that the above description is only one embodiment of the present invention, and all equivalent changes of the system described in the present invention are included in the protection scope of the present invention. Persons skilled in the art to which this invention pertains may substitute similar alternatives for the specific embodiments described, all without departing from the scope of the invention as defined by the claims.
Claims (6)
1. A photovoltaic power generation system with isolated photovoltaic optimizers is characterized in that a plurality of photovoltaic modules (1) are connected in series to form a photovoltaic subgroup string, each photovoltaic subgroup string is connected with one isolated photovoltaic optimizer (2), and all the isolated photovoltaic optimizers (2) are connected in series and then connected with a photovoltaic inverter (3);
the isolated photovoltaic optimizer (2) comprises a full-bridge LL C circuit formed by an input side current-voltage sensor (21), an H-bridge (22), a resonant capacitor (23), a high-frequency transformer (24), a synchronous rectification circuit (25) and an output side current-voltage sensor (26), wherein the input side current-voltage sensor (21) is sequentially connected to the output side, the H-bridge (22) is connected with a control and drive module (27), the control and drive module (27) is further respectively connected with the input side current-voltage sensor (21) and the output side current-voltage sensor (26), and a photoelectric coupler (28) is connected between the control and drive module (27) and the output side current-voltage sensor (26).
2. The photovoltaic power generation system with the isolated photovoltaic optimizer of claim 1, wherein the H-bridge (22) comprises 4 switching tubes, the 4 switching tubes are connected in series two by two, and the two series branches are connected through a central point; the two series branches are connected with an input power supply, and the central point is connected with a resonant capacitor (23).
3. The photovoltaic power generation system with the isolated photovoltaic optimizer of claim 2, wherein the switching tube is a GaN switching tube, a SiC switching tube, or a Si switching tube.
4. The photovoltaic power generation system with the isolated photovoltaic optimizer of claim 1, wherein the control and drive module (27) comprises an MCU (271) and a drive circuit (272), the MCU (271) is connected with the drive circuit (272), the drive circuit (272) is connected with the H-bridge (22), and the MCU (271) is connected with the input side current-voltage sensor (21) and the photocoupler (28), respectively.
5. The photovoltaic power generation system with isolated photovoltaic optimizer of claim 1, wherein the high frequency transformer (24) is a center tapped transformer.
6. The photovoltaic power generation system with the isolated photovoltaic optimizer of claim 1, wherein the synchronous rectification circuit (25) comprises a half-bridge rectification circuit formed by two mosfet tubes.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113829886A (en) * | 2021-09-23 | 2021-12-24 | 中国华能集团清洁能源技术研究院有限公司 | Solar electric automobile |
| CN114281146A (en) * | 2021-11-19 | 2022-04-05 | 华能大理风力发电有限公司洱源分公司 | MPPT control device and MPPT control system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113829886A (en) * | 2021-09-23 | 2021-12-24 | 中国华能集团清洁能源技术研究院有限公司 | Solar electric automobile |
| CN114281146A (en) * | 2021-11-19 | 2022-04-05 | 华能大理风力发电有限公司洱源分公司 | MPPT control device and MPPT control system |
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