CN113131858A - PV string optimizer system - Google Patents

PV string optimizer system Download PDF

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Publication number
CN113131858A
CN113131858A CN202110492365.0A CN202110492365A CN113131858A CN 113131858 A CN113131858 A CN 113131858A CN 202110492365 A CN202110492365 A CN 202110492365A CN 113131858 A CN113131858 A CN 113131858A
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CN
China
Prior art keywords
string
unit
assembly
optimizer
string optimizer
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Pending
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CN202110492365.0A
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Chinese (zh)
Inventor
肖安波
曾建友
周党生
盛小军
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Shenzhen Hopewind Electric Co Ltd
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Shenzhen Hopewind Electric Co Ltd
Priority date (The priority date 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 date listed.)
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Application filed by Shenzhen Hopewind Electric Co Ltd filed Critical Shenzhen Hopewind Electric Co Ltd
Priority to CN202110492365.0A priority Critical patent/CN113131858A/en
Publication of CN113131858A publication Critical patent/CN113131858A/en
Pending legal-status Critical Current

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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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/10—Parallel operation of dc sources
    • 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
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/35—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering with light sensitive cells
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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

Abstract

The invention discloses a PV string optimizer system, which comprises N PV string optimizers, wherein each PV string optimizer corresponds to a PV assembly string, each PV assembly string is formed by connecting at least two PV assemblies in series, the input end of each PV string optimizer is independently connected with the output end of the corresponding PV assembly string for independent maximum power tracking, one PV string optimizer I to one PV string optimizer N are connected to a DC/AC inverter through the corresponding cables I to N, the PV string optimizer system has the functions of maximum power point tracking and short-circuit fault disconnection protection at the same time, each PV component string carries out independent MPPT tracking, when any PV component string has a short circuit, the other PV assembly strings still work normally, the problem of parallel mismatch is avoided, and short-circuit current is continuously generated in the whole loop under the condition that short-circuit faults occur in one PV assembly string.

Description

PV string optimizer system
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a PV string optimizer system.
Background
The existing PV power optimizer is to install one power optimizer for each PV component corresponding to the connection. The technical core of the power optimizer is to realize maximum power point tracking of the PV assembly, and a loop can be cut off when short circuit and other faults exist, so that arcing and fire ignition are prevented, and the like. However, as the cost of PV modules decreases, the cost of the power optimizer is higher than the cost of PV modules, resulting in the cost of a real power plant increasing too much to be practical for mass application.
The existing collecting and distributing type collecting box firstly collects the multi-path PV strings, and then a plurality of PV strings are subjected to maximum power point tracking. The distributed combiner box can solve the problem of parallel mismatch of a plurality of PV strings, but because a plurality of PV strings are introduced into one combiner box, if the combiner box is subjected to a major fault short circuit, all PV string in the combiner box can be caused to be short-circuited. Due to the current limiting characteristic of the PV assembly, overcurrent protection cannot be performed by using a circuit breaker or a fuse, and only the whole loop can continuously generate short-circuit current until a short-circuit point generates heat to cause arc discharge and fire.
There is a need for a PV string optimizer system having both maximum power point tracking and short-circuit fault disconnection protection functions, where each PV module string performs independent MPPT tracking, when any PV module string is short-circuited, other PV module strings still operate normally, and no parallel mismatch problem occurs, and when a short-circuit fault occurs at the rear end of an automatic disconnecting switch of any PV module string, which causes an input overcurrent, the automatic disconnecting switch is automatically disconnected, so that a short-circuit fault of one PV module string is avoided, which causes the whole circuit to continuously generate a short-circuit current.
Disclosure of Invention
The invention aims to solve the technical problem of providing a PV string optimizer system which has the functions of maximum power point tracking and short-circuit fault disconnection protection, each PV component string performs independent MPPT tracking, when any PV component string in one path is in a short-circuit condition, other PV component strings still work normally and the problem of parallel mismatch is avoided, and when the input overcurrent condition is caused by the short-circuit fault occurring at the rear end of the automatic breaking switch of any PV component string in the other path, the automatic breaking switch is automatically disconnected, so that the situation that the short-circuit fault occurs in one PV component string in the other path, the whole loop continuously generates short-circuit current is avoided.
In order to solve the above technical problems, the present invention provides a PV string optimizer system, which includes N PV string optimizers, each PV string optimizer corresponds to a PV module string, each PV module string is formed by connecting at least two PV modules in series, each PV string optimizer input end is independently connected to a corresponding PV module string output end for independent maximum power tracking, the PV string optimizers one to N are connected to an inverter through respective corresponding cables one to N, and PV module types and numbers of any PV module string between the PV module strings one to N may be the same or different.
Preferably, N PV string optimizers and corresponding N PV module strings form a first unit, the inverter in the PV string optimizers system further includes a second unit, and the second unit includes a first input fuse and a DC/AC conversion unit corresponding to each PV string optimizer; the PV string optimizers I to N are connected to corresponding input fuses I in the unit II through independent cables I to N, all input fuses in the inverter are output and converged to form a uniform direct current bus, the PV assembly strings I to N in the unit I are subjected to maximum power tracking and independent control through the PV string optimizers I to N, and the direct current bus is connected with the DC/AC conversion unit.
Preferably, the inverter in the PV string optimizer system further comprises a battery access fuse through which the energy storage battery is connected to the dc bus.
Preferably, N PV string optimizers and corresponding N PV module strings form a first unit, the inverter in the PV string optimizers system further includes a second unit, and the second unit includes a first input fuse and a DC/AC conversion unit corresponding to each PV string optimizer; the PV string optimizers I to N are connected to corresponding input fuses I in the unit II through independent cables I to N; the output of all input fuses I in the inverter is converged to form a uniform direct current bus, the PV string optimizer system further comprises a third unit, the third unit comprises M PV assembly strings which are independent respectively, and the second unit of the inverter further comprises an input fuse II and a DC/AC conversion unit, wherein the input fuse II corresponds to the PV assembly strings I to the PV assembly strings M in the third unit; and the PV assembly string I to the PV assembly string M in the unit III are directly connected in parallel after passing through the input fuse II corresponding to the unit II of the inverter.
Preferably, the PV string optimizer system further comprises a unit four and a battery access fuse, the unit four comprises a DC/DC converter for detecting the state of the energy storage battery and controlling the current and voltage for charging and discharging the energy storage battery according to the instruction of the battery management system, the DC/DC converter is connected with the DC bus through the battery access fuse, and the energy storage battery is connected with the DC/DC converter.
Preferably, each PV string optimizer comprises an automatic breaking switch K1 with short-circuit fault disconnection protection function and a DC/DC converter arranged at the rear end of the automatic breaking switch K1.
Preferably, the PV string optimizer further comprises a control unit for detecting the voltage value at the input end of the PV string optimizer and judging whether the rear end of the automatic breaking switch K1 is short-circuited.
Preferably, the control unit is connected with the automatic breaking switch K1, the input end of the PV string optimizer and the output voltage end of the PV string optimizer.
Preferably, the rear end of the automatic breaking switch K1 is provided with a boosting circuit for boosting the voltage at the output end of the PV string and connecting the boosted output voltage to the outside through an output cable.
Preferably, the automatic breaking switch K1 is connected in series with a positive wire at the input end of the PV string optimizer; or the automatic breaking switch K1 is connected in series on the negative electrode lead; or two automatic breaking switches K1 are respectively connected in series on the positive electrode lead and the negative electrode lead.
After the system is adopted, the PV string optimizer system comprises N PV string optimizers, each PV string optimizer corresponds to one PV assembly string, each PV assembly string is formed by connecting at least two PV assemblies in series, the input end of each PV string optimizer is independently connected with the output end of the corresponding PV assembly string to perform independent maximum power tracking, the PV string optimizers I to N are connected to an inverter through corresponding cables I to N, and the types and the number of PV assemblies of any PV assembly string between the PV assembly strings I to N can be the same or different; the PV assembly string optimizer system has the protection functions of maximum power point tracking and short-circuit fault disconnection, each PV assembly string carries out independent MPPT tracking, when any PV assembly string of one path is in a short-circuit condition, other PV assembly strings still work normally, the problem of parallel mismatch can not occur, when the short-circuit fault occurs at the rear end of the automatic disconnecting switch of any PV assembly string of one path, the automatic disconnecting switch is automatically disconnected under the condition that input overcurrent is caused, and therefore the situation that short-circuit fault occurs in the PV assembly strings of one path, the whole loop continuously generates short-circuit current is avoided.
Drawings
FIG. 1 is a block diagram of a prior art power optimizer connection to a PV;
FIG. 2 is a block diagram of the connection of a prior art collection and distribution header box to a PV;
FIG. 3 is a circuit diagram of the PV string optimizer in connection with a string of PV modules according to the present invention;
FIG. 4 is a circuit diagram of a PV string optimizer of the present invention;
FIG. 5 is a circuit diagram of a PV string optimizer system in accordance with one embodiment of the present invention;
FIG. 6 is a circuit diagram of a PV string optimizer and its photovoltaic system according to a second embodiment of the present invention;
fig. 7 shows a PV string optimizer and its photovoltaic system according to a third embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example one
Referring to fig. 3, 4 and 5, fig. 3 is a circuit diagram of the PV string optimizer and PV module string connection of the present invention, fig. 4 is a circuit diagram of the PV string optimizer of the present invention, and fig. 5 is a circuit diagram of a PV string optimizer system according to an embodiment of the present invention; the embodiment discloses a PV string optimizer system, which includes N PV string optimizers, each PV string optimizer corresponds to a PV module string, each PV module string is composed of at least two PV modules connected in series, each PV string optimizer input end is independently connected with a corresponding PV module string output end for independent maximum power tracking, each PV string optimizer includes an automatic breaking switch K1 with a short-circuit fault breaking protection function and a DC/DC converter arranged at the rear end of the automatic breaking switch K1, and PV string optimizers one to PV string optimizers N are connected to an inverter through corresponding cables one to N;
the PV component strings I to N are respectively connected into a PV string optimizer I to a PV string optimizer N through N pairs of cable bundles, and the output of all the PV string optimizers is connected into an inverter through cables I to N; each PV cluster optimizer is internally provided with an independent Maximum Power Point Tracking (MPPT) unit, the maximum power output tracking of each PV assembly cluster is carried out, each PV cluster is independently connected to the independent PV cluster optimizer to carry out the independent MPPT tracking, the problem of parallel mismatch does not exist, the PV assembly models and the number of any PV assembly cluster between the PV assembly cluster I and the PV assembly cluster N can be the same or different, and the effect of convenient use is achieved.
In this embodiment, the PV string optimizer further includes a control unit for detecting a voltage value at an input terminal of the PV string optimizer and determining whether a short circuit occurs at a rear end of the automatic disconnecting switch K1;
and the control unit is connected with the automatic breaking switch K1, the input end of the PV string optimizer and the output voltage end of the PV string optimizer.
The rear end of the automatic breaking switch K1 is provided with a boosting circuit for boosting the voltage at the output end of the PV string and connecting the boosted output voltage to the outside through an output cable.
In this embodiment, the PV string optimizer is installed with the PV string assembly, the DC/AC inverter device at the output rear end of the PV string optimizer is located at a relatively long distance from the PV string optimizer, and the output voltage Vo of the boost circuit of the PV string optimizer needs to pass through a long-distance output cable to be connected to the DC/AC inverter device at the output rear end of the PV string optimizer, where the output cable has a relatively long distance and is relatively easy to cause a short-circuit fault, and when any one of the cables from one cable to cable N is short-circuited, the control unit of the corresponding PV string optimizer detects an abnormal inductive current and triggers the automatic disconnecting switch K1 of the PV string optimizer to be disconnected, thereby playing a role in preventing the fault from being expanded.
In this embodiment, the DC/AC inverter outputs energy to the power grid to perform grid-connection control, and simultaneously adjusts the total power energy output to ensure the stability of the DC bus voltage.
In this embodiment, the main breaking switch K1 is one of a mechanical switch contactor, a relay, a semiconductor insulated gate bipolar transistor, a metal oxide semiconductor field effect transistor, and a triode.
In the embodiment, the automatic breaking switch K1 is connected in series with the positive wire of the input end of the PV string optimizer; or the automatic breaking switch K1 is connected in series on the negative electrode lead; or two automatic breaking switches K1 are respectively connected in series on the positive electrode lead and the negative electrode lead.
Example two
Referring to fig. 6, fig. 6 is a circuit diagram of a PV string optimizer and a photovoltaic system thereof according to a second embodiment of the present invention; the embodiment discloses a PV string optimizer system, wherein N PV string optimizers and corresponding N PV module strings form a first unit, an inverter in the PV string optimizer system further comprises a second unit, and the second unit comprises a first input fuse and a DC/AC conversion unit, which correspond to each PV string optimizer; the PV string optimizers one to N are connected to the corresponding input fuses one in the unit two through independent cables one to N.
In this embodiment, the PV string optimizer further includes a control unit for detecting a voltage value at an input terminal of the PV string optimizer and determining whether a short circuit occurs at a rear end of the automatic disconnecting switch K1;
and the control unit is connected with the automatic breaking switch K1, the input end of the PV string optimizer and the output voltage end of the PV string optimizer.
The rear end of the automatic breaking switch K1 is provided with a boosting circuit for boosting the voltage at the output end of the PV string and connecting the boosted output voltage to the outside through an output cable.
The PV component strings I to N are respectively connected into a PV string optimizer I to a P string optimizer N through N pairs of cables, the PV string optimizer I to the PV string optimizer N are connected to an input fuse I of the unit II through respective independent cables I to N, an independent Maximum Power Point Tracking (MPPT) unit is arranged in each PV string optimizer for carrying out power output maximization tracking on each PV component string, all input fuses in the unit II are converged to form a unified direct current bus bar, the PV component strings I to PV component strings N in the unit I are subjected to maximum power point tracking and independent control through the PV string optimizer I to the PV string optimizer N, and the direct current bus bar is connected with the DC/AC conversion unit.
In this embodiment, the PV string optimizer system further includes a battery access fuse through which the energy storage battery is connected to the dc bus.
In this embodiment, the inverter outputs energy to a power grid to perform grid-connection control, and adjusts and regulates the voltage of the dc bus bar, that is, the charging and discharging are controlled by the voltage of the energy storage battery, so as to complete the energy control of the inverter.
In this embodiment, the main breaking switch K1 is one of a mechanical switch contactor, a relay, a semiconductor insulated gate bipolar transistor, a metal oxide semiconductor field effect transistor, and a triode.
In the embodiment, the automatic breaking switch K1 is connected in series with the positive wire of the input end of the PV string optimizer; or the automatic breaking switch K1 is connected in series on the negative electrode lead; or two automatic breaking switches K1 are respectively connected in series on the positive electrode lead and the negative electrode lead.
EXAMPLE III
Referring to fig. 7, fig. 7 is a diagram of a PV string optimizer and a photovoltaic system thereof according to a third embodiment of the present invention.
The embodiment discloses a PV string optimizer system, which further includes a unit three on the basis of the PV string optimizer system of the embodiment one, an inverter in the PV string optimizer system further includes a unit two, and the unit two includes an input fuse one and a DC/AC conversion unit corresponding to each PV string optimizer; the PV string optimizers I to N are connected to corresponding input fuses I in the unit II through independent cables I to N; all input fuses I in the inverter are output and converged to form a unified direct current bus, the unit III comprises M PV assembly strings which are independent respectively, and the unit II comprises an input fuse II and a DC/AC conversion unit which correspond to the PV assembly strings I to M in the unit III; and PV assembly strings I to M in the unit III are directly connected in parallel after passing through the input fuse II corresponding to the unit II.
The PV string optimizer system further comprises a unit IV and a battery access fuse, wherein the unit IV comprises a DC/DC converter which is used for detecting the state of the energy storage battery and controlling the current and the voltage for charging and discharging the energy storage battery according to the instruction of the battery management system, the DC/DC converter is connected with the direct current bus through the battery access fuse, and the energy storage battery is connected with the DC/DC converter.
The outputs of the first unit and the third unit are connected to the input fuse of the second unit, the PV module string-to-PV voltage is independently controlled by the PV string-to-PV-string optimizer-to-PV-string-to-PV-module string-to-module-to-PV-to-module-to-PV-to-string-to-module-to-, when the PV module string is used, the model number and the number of the PV module string need to be kept consistent, otherwise, the parallel mismatch and the power generation loss are large.
And the unit four is used for charging the energy storage battery, power is taken from a direct current bus of the PV string optimizer system after passing through a fuse wire in the unit two, the value of the voltage of the direct current bus, namely the input voltage of the DC/DC unit, is determined by a DC/AC inverter in the unit two, the unit four comprises a DC/DC converter which is used for detecting the state of the energy storage battery and controlling the current and the voltage for charging and discharging the energy storage battery according to the instruction of a battery management system, the DC/DC converter is connected with the direct current bus through the battery access fuse wire, and the energy storage battery is connected with the DC/DC converter.
In the embodiment, part of the PV component strings are directly connected in parallel, and part of the PV component strings are connected after passing through the independent PV string optimizer, so that the problem of serious power generation loss caused by great terrain difference in some occasions in reality is well solved.
After the system is adopted, the PV string optimizer system comprises N PV string optimizers, each PV string optimizer corresponds to one PV assembly string, each PV assembly string is formed by connecting at least two PV assemblies in series, the input end of each PV string optimizer is independently connected with the output end of the corresponding PV assembly string to perform independent maximum power tracking, the PV string optimizers I to N are connected to an inverter through corresponding cables I to N, and the types and the number of PV assemblies of any PV assembly string between the PV assembly strings I to N can be the same or different; the PV assembly string optimizer system has the protection functions of maximum power point tracking and short-circuit fault disconnection, each PV assembly string carries out independent MPPT tracking, when any PV assembly string of one path is in a short-circuit condition, other PV assembly strings still work normally, the problem of parallel mismatch can not occur, when the short-circuit fault occurs at the rear end of the automatic disconnecting switch of any PV assembly string of one path, the automatic disconnecting switch is automatically disconnected under the condition that input overcurrent is caused, and therefore the situation that short-circuit fault occurs in the PV assembly strings of one path, the whole loop continuously generates short-circuit current is avoided.
It should be understood that the above is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent flow transformations made by the present specification and drawings, or applied directly or indirectly to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A PV string optimizer system is characterized by comprising N PV string optimizers, each PV string optimizer corresponds to one PV assembly string, each PV assembly string is formed by connecting at least two PV assemblies in series, each PV string optimizer input end is independently connected with the corresponding PV assembly string output end for independent maximum power tracking, one PV string optimizer to one PV string optimizer N are connected to an inverter through corresponding cables from one PV assembly string to the other PV assembly string, and the types and the number of PV assemblies of any PV assembly string from the one PV assembly string to the PV assembly string N can be the same or different.
2. The PV string optimizer system of claim 1, wherein N PV string optimizers and corresponding N PV module strings form a first unit, wherein the inverter in the PV string optimizer system further comprises a second unit comprising a first input fuse corresponding to each PV string optimizer, a DC/AC conversion unit; the PV string optimizers I to N are connected to corresponding input fuses I in the unit II through independent cables I to N, all input fuses in the inverter are output and converged to form a uniform direct current bus, the PV assembly strings I to N in the unit I are subjected to maximum power tracking and independent control through the PV string optimizers I to N, and the direct current bus is connected with the DC/AC conversion unit.
3. The PV string optimizer system of claim 2, wherein the inverter in the PV string optimizer system further comprises a battery access fuse through which the energy storage battery is connected to the dc bus.
4. The PV string optimizer system of claim 1, wherein N PV string optimizers and corresponding N PV module strings form a first unit, wherein the inverter in the PV string optimizer system further comprises a second unit comprising a first input fuse corresponding to each PV string optimizer, a DC/AC conversion unit; the PV string optimizers I to N are connected to corresponding input fuses I in the unit II through independent cables I to N; the output of all input fuses I in the inverter is converged to form a uniform direct current bus, the PV string optimizer system further comprises a third unit, the third unit comprises M PV assembly strings which are independent respectively, and the second unit of the inverter further comprises an input fuse II and a DC/AC conversion unit, wherein the input fuse II corresponds to the PV assembly strings I to the PV assembly strings M in the third unit; and the PV assembly string I to the PV assembly string M in the unit III are directly connected in parallel after passing through the input fuse II corresponding to the unit II of the inverter.
5. The PV string optimizer system according to claim 4 further comprising a unit four including a DC/DC converter for detecting the state of the energy storage battery and controlling the amount of current and voltage to be charged and discharged to and from the energy storage battery according to the instructions of the battery management system, wherein the DC/DC converter is connected to the DC bus via the battery access fuse, and wherein the energy storage battery is connected to the DC/DC converter.
6. The PV string optimizer system according to claim 1, wherein each PV string optimizer comprises an automatic disconnect switch K1 with short-circuit fault disconnect protection and a DC/DC converter disposed at the back end of the automatic disconnect switch K1.
7. The PV string optimizer system of claim 6, wherein the PV string optimizer further comprises a control unit that detects PV string optimizer input voltage values and determines whether a short circuit occurs at the back end of the automatic disconnect switch K1.
8. The PV string optimizer system according to claim 7, wherein the control unit is connected to an automatic disconnect switch K1, a PV string optimizer input, a PV string optimizer output voltage terminal.
9. The PV string optimizer system according to claim 6, wherein the automatic disconnect switch K1 is provided at the back end with a voltage boosting circuit for boosting the voltage at the output end of the PV string and connecting the boosted output voltage to the outside through an output cable.
10. The PV string optimizer system according to claim 6, wherein the automatic disconnect switch K1 is connected in series on the positive conductor at the input of the PV string optimizer; or the automatic breaking switch K1 is connected in series on the negative electrode lead; or two automatic breaking switches K1 are respectively connected in series on the positive electrode lead and the negative electrode lead.
CN202110492365.0A 2021-05-06 2021-05-06 PV string optimizer system Pending CN113131858A (en)

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Application Number Priority Date Filing Date Title
CN202110492365.0A CN113131858A (en) 2021-05-06 2021-05-06 PV string optimizer system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110492365.0A CN113131858A (en) 2021-05-06 2021-05-06 PV string optimizer system

Publications (1)

Publication Number Publication Date
CN113131858A true CN113131858A (en) 2021-07-16

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