CN113541605A - Photovoltaic inverter, photovoltaic inverter system and control method - Google Patents

Photovoltaic inverter, photovoltaic inverter system and control method Download PDF

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Publication number
CN113541605A
CN113541605A CN202110885976.1A CN202110885976A CN113541605A CN 113541605 A CN113541605 A CN 113541605A CN 202110885976 A CN202110885976 A CN 202110885976A CN 113541605 A CN113541605 A CN 113541605A
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CN
China
Prior art keywords
unit
string
inverter
photovoltaic inverter
photovoltaic
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Pending
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CN202110885976.1A
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Chinese (zh)
Inventor
李宁
卢盈
吴生闻
张勇
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Esway New Energy Technology Jiangsu Co ltd
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Esway New Energy Technology Jiangsu Co ltd
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Priority to CN202110885976.1A priority Critical patent/CN113541605A/en
Publication of CN113541605A publication Critical patent/CN113541605A/en
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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
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
    • H02H11/002—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection
    • 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
    • H02H7/10—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 converters; for rectifiers
    • H02H7/12—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 converters; for rectifiers for static converters or rectifiers
    • H02H7/122—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 converters; for rectifiers for static converters or rectifiers for inverters, i.e. dc/ac converters
    • 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

Abstract

The invention discloses a photovoltaic inverter, a photovoltaic inverter system and a control method, wherein the photovoltaic inverter comprises a DC-DC conversion unit, a DC-LINK capacitor bank and a DC-AC conversion unit which are sequentially connected, the photovoltaic inverter also comprises a PV input end which is used for connecting a photovoltaic string, the photovoltaic inverter also comprises a string detection device which is used for detecting whether the accessed photovoltaic string is reversely connected, and the string detection device comprises: the current detection unit is used for detecting the current of the PV input end and outputting a detection signal; a comparator unit for comparing a voltage value of the detection signal with a reference voltage and outputting a signal indicating that the strings are reversely connected when a set condition is satisfied; the power supply energy storage unit is used for supplying power to the current detection unit and the comparator unit; a photovoltaic inverter includes: the first charging unit is used for charging the power supply energy storage unit. The photovoltaic inverter can accurately detect the reverse connection condition of the PV string when the photovoltaic inverter is not connected to a power grid power supply and all strings are reversely connected.

Description

Photovoltaic inverter, photovoltaic inverter system and control method
Technical Field
The invention belongs to the field of photovoltaic inverters, and relates to a photovoltaic inverter, a photovoltaic inverter system and a control method.
Background
The photovoltaic inverter is a core device for converting direct current provided by a Solar module into alternating current for civil use or industrial use, and the position of the photovoltaic inverter in the field of new energy is more and more important. In recent years, with the planning of carbon peak reaching and carbon neutralization, the green energy comes with explosive development, and the installation capacity of a photovoltaic module machine power generation system is larger and larger, so that the photovoltaic module machine power generation system becomes the main force of the current green energy. Because the photovoltaic module is often in the problem of the reverse connection of the photovoltaic panel group string (hereinafter referred to as the photovoltaic group string) in the construction and installation of the inverter, how to efficiently and quickly identify the reverse connection group string and give an alarm has important practical significance in guiding an installer to timely perform connection adjustment and maintenance. However, the existing photovoltaic string reverse connection detection technology utilizes a current sensor to collect string input current to judge whether reverse connection exists, and the reverse connection condition cannot be accurately detected under the condition that all photovoltaic strings are in reverse connection and are not connected to a power grid power supply.
Disclosure of Invention
In view of the above technical problems, an object of the present invention is to provide a photovoltaic inverter and a photovoltaic inverter system, which can accurately detect the reverse connection condition of PV strings when not accessing a power grid power supply and when all strings are reverse connected.
Another object of the present invention is to provide a control method for a photovoltaic inverter, which can accurately detect the reverse connection condition of PV strings when the PV strings are not connected to a power grid and all the strings are connected in reverse.
The invention adopts the following technical scheme:
a photovoltaic inverter comprising a DC-DC conversion unit, a DC-LINK capacitor bank and a DC-AC conversion unit connected in sequence, said photovoltaic inverter further having a PV input for connecting a string of photovoltaic banks, said photovoltaic inverter further comprising a string detection device for detecting whether an accessed string of photovoltaic banks is connected in reverse, said string detection device being connected between said PV input and said DC-DC conversion unit, said string detection device comprising:
the current detection unit is used for detecting the current of the PV input end and outputting a detection signal;
the input end of the comparator unit is connected with the output end of the current detection unit and is used for comparing the voltage value of the detection signal with a reference voltage, and the comparator unit outputs a signal representing that the group is in reverse connection when a set condition is met; and
the power supply energy storage unit is respectively connected with the current detection unit and the comparator unit to supply power to the current detection unit and the comparator unit;
the photovoltaic inverter includes:
the first charging unit is used for charging the power supply energy storage unit, the input end of the first charging unit is connected with the DC-LINK capacitor bank, and the output end of the first charging unit is connected with the power supply energy storage unit.
Preferably, the string detection device further includes a second charging unit for charging the power storage unit, an input end of the second charging unit is connected to an AC side of the DC-AC conversion unit, and an output end of the second charging unit is connected to the power storage unit.
Preferably, the photovoltaic inverter further comprises a control unit, and the output end of the comparator unit is connected with the control unit.
Preferably, the string detection device further comprises an alarm unit, the alarm unit is connected with the output end of the comparator unit, and the power storage unit is connected with the alarm unit to supply power to the alarm unit. By introducing the alarm unit, the great convenience of installation and maintenance is realized, and the display significance is important.
Preferably, the alarm unit comprises a status indicator light.
Preferably, a non-inverting input terminal of the comparator unit is connected to the reference voltage, and an inverting input terminal of the comparator unit is connected to an output terminal of the current detection unit.
Preferably, the photovoltaic inverter includes a plurality of groups of PV input ends and a plurality of group string detection devices, each group of PV input ends is used for accessing a photovoltaic group string of one path, each group of PV input ends is connected with a corresponding group string detection device, and an output end of the first charging unit is connected with the power storage unit of each group string detection device.
Preferably, the setting conditions are: the voltage value of the detection signal is smaller than the reference voltage.
Preferably, the power storage unit is a super capacitor.
The invention also adopts the following technical scheme:
a photovoltaic inverter system comprises a photovoltaic string and a photovoltaic inverter, wherein the photovoltaic inverter adopts the photovoltaic inverter, and the output end of the photovoltaic string is directly connected to the PV input end of the photovoltaic inverter.
The invention also adopts the following technical scheme:
a control method of a photovoltaic inverter, the photovoltaic inverter being the photovoltaic inverter as described above, the control method comprising the steps of:
under the working condition of maintenance or repair, the first charging unit does not work, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series connection;
under the working condition of maintenance or repair, the first charging unit works, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series reverse connection;
under the working condition that the photovoltaic inverter is not connected with a power grid, the second charging unit does not work, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-parallel connection;
under the working condition that the photovoltaic inverter is connected with the power grid, the second charging unit works, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series connection.
Preferably, the signal indicating that the string is reversely connected, which is output by the comparator unit, is sent to the control unit of the photovoltaic inverter, or is sent to the alarm unit of the string detection device to enable the alarm unit to alarm.
Compared with the prior art, the invention has the following advantages by adopting the scheme:
according to the photovoltaic inverter, the photovoltaic inverter system and the control method, the string detection device is integrated in the photovoltaic inverter, the string detection unit comprises the power supply energy storage unit capable of supplying power to the string detection unit, the function of intelligently detecting the reverse connection of the strings in the full working condition or when all the PV strings are in reverse connection can be realized, the difficulty of the reverse connection of the outgoing lines of the photovoltaic strings in the actual installation application is effectively solved, the photovoltaic strings can be realized without being communicated with a power grid, and the convenience and the safety of installation and maintenance are effectively guaranteed.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a circuit diagram of a photovoltaic inverter and photovoltaic inverter system according to an embodiment;
fig. 2 is a circuit diagram of a string detection apparatus.
Wherein the content of the first and second substances,
1. a photovoltaic string; 2. a string detection device; 3. a DC-DC conversion unit; 4. a DC-LINK capacitor bank; 5. a DC-AC conversion unit; 6. a first charging unit; 7. a second charging unit; 8. a control unit; 9. a power grid; 10. a photovoltaic inverter; 11. a current detection unit; 12. a comparator unit; 13. a power supply energy storage unit; 14. and an alarm unit.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention may be more readily understood by those skilled in the art. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the present embodiment provides a photovoltaic inverter 10, which includes a string detection device 2, a DC-DC conversion unit 3, a DC-LINK capacitor bank 4, and a DC-AC conversion unit 5, which are connected in sequence. The input end of the string detection device 2 is connected with the PV input end PV + and PV-, and whether the accessed photovoltaic string is reversely connected is detected. PV input ends PV + and PV-are provided with a plurality of groups, the group string detection device 2 is correspondingly provided with a plurality of groups, each group of PV input ends PV + and PV-is used for being connected with one path of photovoltaic group string 1, the photovoltaic group string 1 is grounded, and each group of PV input ends PV + and PV-is respectively connected with a corresponding group string detection device 2. The output end of the string detection device 2 is connected with the DC-DC conversion unit 3, the electric energy output by the PV input ends PV + and PV-is connected to the DC-DC conversion unit 3 through the string detection device 2, and the electric energy of the DC-DC conversion unit 3 can supply power to the DC-LINK capacitor bank 4.
The photovoltaic inverter 10 further includes: a first charging unit 6 and a second charging unit 7, and a control unit 8. The first charging unit 6 is used for charging the power supply energy storage unit 13, the input end of the first charging unit 6 is connected with the DC-LINK capacitor bank 4, the output end of the first charging unit 6 is connected with the power supply energy storage unit 13, the output end of the first charging unit 6 is further connected with the DC-AC conversion unit 5 to supply power to the DC-AC conversion unit, and the first charging unit 6 specifically comprises a switching power supply DC-SPS. And the second charging unit 7 is also used for charging the power energy storage unit 13, the input end of the second charging unit 7 is connected with the alternating current side of the DC-AC conversion unit 5, and the second charging unit 7 specifically comprises a switching power supply AC-SPS. The output ends of the first charging unit 6 and the groups of string detection devices 2 are respectively connected with the control unit 8, the DC-DC conversion unit 3 and the DC-AC conversion unit 5 are respectively connected with the control unit 8 for signal transmission, and the first charging unit 6 and the second charging unit 7 can both supply power for the control unit 8.
As shown in fig. 2, each of the sets of string detection devices 2 includes: a current detection unit 11 for detecting the current of the PV input terminals PV + and PV-and outputting a detection signal, wherein the current detection unit 11 outputs Vout to be connected to the control unit 8 for detecting the string current and determining the abnormality; a comparator unit 12, an input end of which is connected to the output end of the current detection unit 11, and is configured to compare the voltage value of the detection signal with the reference voltage, and when the voltage value of the detection signal is smaller than the reference voltage, the comparator unit 12 outputs a signal indicating that the group is in series-to-series connection, specifically in this embodiment, a non-inverting input end of the comparator unit 12 is connected to the reference voltage, and an inverting input end of the comparator unit is connected to the output end of the current detection unit 11; the power supply energy storage unit 13 is respectively connected with the current detection unit 11 and the comparator unit 12 to supply power to the current detection unit 11 and the comparator unit 12, specifically, in this embodiment, the power supply energy storage unit 13 is a super capacitor, the output end of the first charging unit 6 is respectively connected with the power supply energy storage units 13 of the groups of string detection devices 2, and the output end of the second charging unit 7 is connected with the power supply energy storage unit 13; and the alarm unit 14 is connected with the output end of the comparator unit 12, and the alarm unit 14 comprises a status indicator lamp which can alarm after receiving the enabling signal output by the comparator, namely the indicator lamp is turned on. The photovoltaic inverter 10 further includes a voltage input terminal Vcc, and the voltage input terminal Vcc is respectively connected to the power storage unit 13, the current detection unit 11, and the alarm unit 14 to supply power to the power storage unit 13, the current detection unit 11, and the alarm unit 14. Both the first charging unit 6 and the second charging unit 7 may supply power to the string detection device 2.
The embodiment also adopts the following technical scheme:
as shown in fig. 1, a photovoltaic inverter system includes a photovoltaic string 1 and a photovoltaic inverter, the photovoltaic inverter employs the photovoltaic inverter 10 as described above, the output end of the photovoltaic string is directly connected to PV input ends PV + and PV-of the photovoltaic inverter 10, there are multiple sets of PV input ends PV + and PV-, and there are multiple sets of string detection devices 2, each set of PV input ends PV + and PV-is used for accessing a photovoltaic string, each set of PV input ends PV + and PV-is respectively connected to a corresponding string detection device 2, and each set of PV input ends PV + and PV-is respectively grounded. The alternating current side of the DC-AC conversion unit 5 is connected to the power grid 9, the DC-LINK capacitor bank 4 can convert the direct current into the alternating current through the DC-AC conversion unit 5 and connect to the power grid 9, and the electric energy of the power grid 9 can be synchronously supplied to the second charging unit 7.
The embodiment also adopts the following technical scheme:
a control method of a photovoltaic inverter, implemented based on the photovoltaic inverter 10 as described above, the control method comprising the steps of:
when a part of photovoltaic string 1 is reversely connected, and is usually under the maintenance or repair working condition, and the DC-SPS unit does not work (the voltage of the non-reversely connected string is lower than the working voltage of the DC-SPS unit), the string detection device 2 is powered by the power storage unit 13, the output signal Vout of the current detection unit 11 is compared with the reference voltage Vref through the comparator unit 12, if Vout < Vref, the comparator unit 12 outputs a signal indicating that the string is reversely connected, and the comparator unit 12 outputs an enable signal to enable the alarm unit 14 connected thereto to alarm (for example, a status light indication);
when a part of photovoltaic string 1 is reversely connected, and is usually under a maintenance or repair working condition, and the DC-SPS unit works (the voltage of the non-reverse-connected string is higher than the working voltage of the DC-SPS unit), the string detection device 2 is powered by the DC-SPS unit, the output signal Vout of the current detection unit 11 is compared with the reference voltage Vref through the comparator unit 12, if Vout is less than Vref, the comparator unit 12 outputs a signal indicating that the string is reversely connected, the comparator unit 12 outputs an enable signal to enable the alarm unit 14 connected with the comparator unit to alarm (for example, a status light indication), and the control unit 8 also detects abnormal string current information and sends the reverse-connected string information to an upper inverter for monitoring and the like;
when all the photovoltaic string strings 1 are reversely connected, at this time, the photovoltaic inverter 10 is usually in a working condition that the photovoltaic inverter is not connected to a power grid, and the AC-SPS unit does not work (the inverter power grid is not connected or the AC-SPS unit is not connected), the string detection device 2 is powered by the power storage unit 13, an output signal Vout of the current detection unit 11 is compared with a reference voltage Vref through the comparator unit 12, if Vout < Vref, the comparator unit 12 outputs a signal indicating that the string is reversely connected, and the comparator outputs an enable signal to enable the alarm unit 14 connected with the comparator to alarm (for example, a status light indicates);
when all the photovoltaic string strings 1 are reversely connected, and normally under the working condition that the photovoltaic inverter 10 is connected with a power grid at the moment, the AC-SPS unit works (inverter power grid connection), the string detection device 2 is powered by the AC-SPS unit, an output signal Vout of the current detection unit 11 is compared with a reference voltage Vref through the comparator unit 12, if Vout is less than Vref, the comparator unit 12 outputs a signal indicating that the string is reversely connected, the comparator outputs an enable signal to enable the alarm unit 14 connected with the comparator to alarm (for example, a status light indication), and the control unit 8 also detects string current abnormal information and sends the string reverse connection information to an upper computer of the inverter for monitoring and the like.
The photovoltaic inverter and the photovoltaic inverter system provided by the embodiment comprise a string detection device 2 connected between a PV input end PV + and a PV-and DC-DC conversion unit 3, the string detection device 2 is integrated in a photovoltaic inverter 10, a current detection unit 11 in the string detection device 2 outputs a signal to be compared with a reference voltage, a comparator unit 12 can output a signal representing reverse connection of a string to an alarm unit 14 for alarm according to a comparison result, and detection of reverse connection of a photovoltaic string 1 under all working conditions (maintenance or maintenance stage, installation stage) of the inverter can be realized; besides, the photovoltaic inverter 10 can intelligently detect the condition that all the photovoltaic strings 1 are reversely connected except the condition that part of the photovoltaic strings 1 are reversely connected; meanwhile, the current detection unit 11 can be powered by the power storage unit 13, so that whether the inverter is connected with a power grid or not, or whether the first charging unit 6 and the second charging unit 7 work normally or not, the photovoltaic inverter system can intelligently identify and detect the reverse connection condition of the photovoltaic string 1, and alarm in a manner that the indicator lamp is turned on. This photovoltaic inverter system has not only effectually solved how to detect the problem that whether the photovoltaic group cluster 1 joins conversely, also can quick accurate ground intelligent identification and report an emergency and ask for help or increased vigilance under the circumstances that does not insert the electric wire netting power and all group clusters all join conversely moreover, very big assurance convenience and the validity of using, through the introduction of warning unit 14, guaranteed convenience and the security of installation and maintenance effectively, have important demonstration meaning. According to the control method of the photovoltaic inverter, the function of intelligently detecting the reverse connection of the photovoltaic string 1 under the full working condition or when the photovoltaic string 1 is completely reversely connected can be achieved, the difficulty of the reverse connection of the photovoltaic string 1 during actual installation and application is effectively solved, the detection can be achieved without connecting a power grid, and the convenience and the safety of installation and maintenance are effectively guaranteed.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are preferred embodiments, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A photovoltaic inverter comprising a DC-DC conversion unit, a DC-LINK capacitor bank and a DC-AC conversion unit connected in sequence, said photovoltaic inverter further having a PV input for connecting a string of photovoltaic banks, characterized in that said photovoltaic inverter further comprises a string detection device for detecting whether an accessed string of photovoltaic banks is connected in reverse, said string detection device being connected between said PV input and said DC-DC conversion unit, said string detection device comprising:
the current detection unit is used for detecting the current of the PV input end and outputting a detection signal;
the input end of the comparator unit is connected with the output end of the current detection unit and is used for comparing the voltage value of the detection signal with a reference voltage, and the comparator unit outputs a signal representing that the group is in reverse connection when a set condition is met; and
the power supply energy storage unit is respectively connected with the current detection unit and the comparator unit to supply power to the current detection unit and the comparator unit;
the photovoltaic inverter includes:
the first charging unit is used for charging the power supply energy storage unit, the input end of the first charging unit is connected with the DC-LINK capacitor bank, and the output end of the first charging unit is connected with the power supply energy storage unit.
2. The pv inverter of claim 1, wherein the string detection device further comprises a second charging unit for charging the power storage unit, an input of the second charging unit is connected to the AC side of the DC-AC conversion unit, and an output of the second charging unit is connected to the power storage unit.
3. The pv inverter of claim 1, further comprising a control unit, wherein the output of the comparator unit is connected to the control unit.
4. The pv inverter of claim 1 wherein the string detection device further comprises an alarm unit, the alarm unit being connected to an output of the comparator unit, the power storage unit being connected to the alarm unit to provide power thereto.
5. The pv inverter of claim 1, wherein the comparator unit has a non-inverting input connected to the reference voltage and an inverting input connected to the output of the current detection unit.
6. The PV inverter of claim 1, wherein the PV inverter comprises a plurality of PV input terminals and a plurality of string detection devices, each PV input terminal is configured to access a string of PV strings, each PV input terminal is connected to a corresponding string detection device, and the output terminal of the first charging unit is connected to the power storage unit of each string detection device.
7. The photovoltaic inverter according to claim 1, wherein the set condition is: the voltage value of the detection signal is smaller than the reference voltage; and/or the power supply energy storage unit is a super capacitor.
8. A PV inverter system comprising a string of PV strings and a PV inverter, wherein the PV inverter employs the PV inverter of any of claims 1 to 7, and wherein the output of the string of PV strings is directly connected to the PV input of the PV inverter.
9. A control method of a photovoltaic inverter, characterized in that the photovoltaic inverter is the photovoltaic inverter according to any one of claims 1 to 7, the control method comprising the steps of:
under the working condition of maintenance or repair, the first charging unit does not work, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series connection;
under the working condition of maintenance or repair, the first charging unit works, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series reverse connection;
under the working condition that the photovoltaic inverter is not connected with a power grid, the second charging unit does not work, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-parallel connection;
under the working condition that the photovoltaic inverter is connected with the power grid, the second charging unit works, and if the voltage value of the detection signal is smaller than the reference voltage, the comparator unit outputs a signal representing that the groups are in series-to-series connection.
10. Control method according to claim 9, characterized in that the signal output by the comparator unit indicating a string reversal is sent to a control unit of the photovoltaic inverter or to an alarm unit of the string detection device to enable the alarm unit to alarm.
CN202110885976.1A 2021-08-03 2021-08-03 Photovoltaic inverter, photovoltaic inverter system and control method Pending CN113541605A (en)

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CN202110885976.1A CN113541605A (en) 2021-08-03 2021-08-03 Photovoltaic inverter, photovoltaic inverter system and control method

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Application Number Priority Date Filing Date Title
CN202110885976.1A CN113541605A (en) 2021-08-03 2021-08-03 Photovoltaic inverter, photovoltaic inverter system and control method

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Publication Number Publication Date
CN113541605A true CN113541605A (en) 2021-10-22

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