WO2016107176A1 - 一种光伏系统 - Google Patents

一种光伏系统 Download PDF

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Publication number
WO2016107176A1
WO2016107176A1 PCT/CN2015/086244 CN2015086244W WO2016107176A1 WO 2016107176 A1 WO2016107176 A1 WO 2016107176A1 CN 2015086244 W CN2015086244 W CN 2015086244W WO 2016107176 A1 WO2016107176 A1 WO 2016107176A1
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WIPO (PCT)
Prior art keywords
string
converter
current
photovoltaic cell
controller
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Ceased
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PCT/CN2015/086244
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English (en)
French (fr)
Inventor
石磊
叶飞
刘云峰
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Publication date
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Priority to JP2017516712A priority Critical patent/JP2017530680A/ja
Priority to EP15874865.7A priority patent/EP3174196A4/en
Publication of WO2016107176A1 publication Critical patent/WO2016107176A1/zh
Priority to US15/493,370 priority patent/US20170222440A1/en
Anticipated expiration legal-status Critical
Ceased 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
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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 feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; 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 feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/46—Controlling the sharing of generated power between the generators, sources or networks
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/084—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters using a control circuit common to several phases of a multi-phase system
    • 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
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/95—Circuit arrangements
    • H10F77/953—Circuit arrangements for devices having potential barriers
    • H10F77/955—Circuit arrangements for devices having potential barriers for photovoltaic devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2101/00—Supply or distribution of decentralised, dispersed or local electric power generation
    • H02J2101/20—Dispersed power generation using renewable energy sources
    • H02J2101/22—Solar energy
    • H02J2101/24—Photovoltaics
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • 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
    • 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

Definitions

  • the present invention relates to the field of electronic technologies, and in particular, to a photovoltaic system.
  • photovoltaic cells are connected in series and parallel to provide output voltage and output current to the load.
  • one of the photovoltaic cell strings is short-circuited, it may cause other photovoltaic cell strings to inject a reverse current into the short-circuited photovoltaic cell string. If the reverse current is greater than the short-circuit current of the photovoltaic cell, the failed photovoltaic cell string may be caused. Burning, even in a serious situation, even a fire, so the need to increase the corresponding protective measures for the photovoltaic string to avoid major accidents.
  • each photovoltaic cell string is connected to a current sensor, each current sensor detects the current of each photovoltaic cell string in real time, and when the current sensor detects a reverse current of a certain photovoltaic cell string, the reverse current is Reported to the controller, the controller controls the converter to reduce the reverse current of the photovoltaic string to protect the photovoltaic cell.
  • each photovoltaic cell string needs to be connected to a current sensor, resulting in an increase in equipment cost.
  • the present invention provides a photovoltaic system. Not only can photovoltaic cell protection be provided, but equipment costs are reduced.
  • a first aspect of the present invention provides a photovoltaic cell protection circuit comprising: a plurality of photovoltaic cell strings, a converter, a controller, and a bus bar, the plurality of photovoltaic cell strings including at least one of two or three photovoltaic cells connected in series Connecting a series of current sensors, the at least one string is connected in parallel to the converter through the bus, the converter is connected to the controller, and the controller and the at least one string respectively a current sensor connection in each of the string groups, for the current sensor Detecting the total current of each string group, and reporting to the controller whether there is a reverse current in each string group, the controller is configured to receive the at least one reported by the current sensor Adjusting a control signal output to the converter when there is a reverse current in the target string group in the string group, the converter for reducing the system voltage between the bus bars to reduce according to the adjusted control signal Reverse current in the target string.
  • the plurality of photovoltaic cell strings further includes a string connected by a photovoltaic cell string and a current sensor, the string connected by a photovoltaic cell string and a current sensor Connected to the converter via the bus bar in parallel with the at least one string connected by two or three photovoltaic cell strings in parallel and connected to the current sensor, the string connected by a photovoltaic cell string and a current sensor A current sensor is connected to the controller.
  • the converter includes a switch tube, a first capacitor, an inductor, and a first diode, wherein:
  • One end of the inductor is connected to an input end of the converter, and the other end of the inductor is respectively connected to a collector of the switch tube and an anode of the first diode, the first diode
  • the negative pole is connected to one end of the first capacitor, and the other end of the first capacitor is respectively connected to the emitter stage of the switch tube and the output end of the converter.
  • the controller includes a processor and a driver, where:
  • the processor is configured to determine whether a reverse current in the target string group is greater than the preset threshold
  • the driver is coupled to the processor, and configured to: when the processor determines that the reverse current in the target string group is greater than the preset threshold, adjust a control signal output to the converter.
  • the controller further includes an analog-to-digital converter, the analog-to-digital converter is coupled to the processor And converting an analog signal of the reverse current reported by the current sensor into a digital signal of a reverse current, and outputting the digital signal of the reverse current to the processor.
  • the converter further includes a second capacitor, one end of the second capacitor and one end of the inductor Connected, the other end of the second capacitor is connected to the emitter stage of the switch tube, and the second capacitor is used for filtering the input voltage.
  • a photovoltaic system comprises a plurality of photovoltaic cell strings, a converter, a controller and a bus bar, the plurality of photovoltaic cell strings comprising at least one string group connected by two or three photovoltaic cells in series and connected to the current sensor, at least one string
  • the groups are connected in parallel and connected to the converter through a busbar.
  • the converter is connected to the controller, and the controller is respectively connected with a current sensor in each of the at least one string group, and the current sensor is used to detect the total current of each string group.
  • the controller is configured to adjust a control signal output to the converter when receiving a reverse current in the target string group in the at least one string group reported by the current sensor,
  • the converter is used to reduce the system voltage between the bus bars according to the adjusted control signal to reduce the reverse current in the target string, thereby providing not only photovoltaic cell protection but also equipment cost.
  • FIG. 1 is a schematic structural view of a photovoltaic system according to an embodiment of the present invention.
  • FIG. 2 is a schematic structural diagram of a converter in a photovoltaic system according to an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a controller in a photovoltaic system according to an embodiment of the present invention.
  • Figure 4 is a graph of the operational V-I of a photovoltaic cell string.
  • FIG. 1 is a schematic structural diagram of a photovoltaic system according to an embodiment of the present invention.
  • the photovoltaic system includes a plurality of photovoltaic cell strings, a converter, a controller, and a bus bar, and the plurality of photovoltaic cell strings includes at least one string group connected by two or three photovoltaic cells in series and connected to the current sensor.
  • the at least one string group is connected in parallel and connected to the converter through the bus bar (1, 2), and the converter is connected to the controller, and the controller is respectively connected with the current sensor in each of the at least one string group, the current sensor And detecting, by the controller, whether there is a reverse current in each of the string groups, and the controller is configured to receive the at least one string group reported by the current sensor When there is a reverse current in the target string group, the control signal output to the converter is adjusted, and the converter is configured to reduce the system voltage between the bus lines (1, 2) according to the adjusted control signal to reduce the target string. Reverse current in the group.
  • the plurality of photovoltaic cell strings further comprise a string group connected by a photovoltaic cell string and a current sensor, the string group connected by a photovoltaic cell string and a current sensor and the at least one photo by two or three photovoltaics
  • the series connected to the current sensors are connected in parallel and connected to the converter through the bus bars (1, 2), and the current sensors in the string connected by a photovoltaic cell string and the current sensor are connected to the controller.
  • the converter includes a switch tube, a first capacitor C1, an inductor L, and a first diode D1, wherein: one end of the inductor L is connected to the input end of the converter, and the other end of the inductor L Connected to the collector of the switch tube and the anode of the first diode D1, the cathode of the first diode D1 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is respectively connected to the emitter stage of the switch tube. And the output terminal of the converter is connected.
  • the converter further includes a second capacitor C2, one end of the second capacitor C2 is connected to one end of the inductor L, the other end of the second capacitor C2 is connected to the emitter stage of the switch tube, and the second capacitor C2 is used for the input.
  • the voltage is filtered.
  • the controller includes a processor 302 and a driver 303, where:
  • the processor 302 is configured to determine whether a reverse current in the target string group is greater than the preset threshold.
  • the driver 303 is connected to the processor, and is configured to adjust a control signal output to the converter when the processor determines that the reverse current in the target string group is greater than the preset threshold.
  • the controller further includes an analog-to-digital converter 301, and the analog-to-digital converter 301 is connected to the processor 302, for converting the analog signal of the reverse current reported by the current sensor into a digital signal of a reverse current. And outputting the digital signal of the reverse current to the processor.
  • the controller when the string of reverse current includes a photovoltaic cell string, the controller adjusts a control signal output to the converter, and the converter reduces the bus according to the adjusted control signal (1) The system voltage between 2) reduces the reverse current of the string to less than the short circuit current of the photovoltaic cell.
  • the controller adjusts the control signal output to the converter, and the converter lowers the bus (1, 2) according to the adjusted control signal The system voltage between them reduces the reverse current of the string to zero.
  • the photovoltaic system includes n string groups, n string groups include m photovoltaic cell strings, the first string group includes 1 photovoltaic cell string, and the second string group includes 3 photovoltaic cell strings.
  • the nth string includes 2 photovoltaic cell strings.
  • the output currents of the other photovoltaic cell strings 2 to the photovoltaic cell string m are current maximum values I sc , resulting in the photovoltaic cell string 2 - the photovoltaic cell string m to the photovoltaic cell string 1
  • the reverse current (m-1) I sc is injected, and the current sensor T1 detects that the first string has a reverse current and the current value of the reverse current is (m-1) I sc .
  • the output current of the photovoltaic cell string 2 to the photovoltaic cell string m is the current maximum value I sc , resulting in the photovoltaic cell string 2 - the photovoltaic cell string m to the photovoltaic cell string 1
  • the reverse current (m-1) I sc is injected.
  • the current sensor T2 detects the reverse current of the second series and the current value of the reverse current is (m-3) I sc .
  • the output current of the photovoltaic cell string 2 to the photovoltaic cell string m is the current maximum value I sc , resulting in the photovoltaic cell string 2 - the photovoltaic cell string m to the photovoltaic cell string 1
  • the reverse current (m-1) I sc is injected, at which time the current sensor Tn detects a reverse current in the second series and the current value of the reverse current is (m-2) I sc .
  • the current sensor reports the reverse current to the controller.
  • the controller determines that the reverse current is greater than a preset threshold, the controller increases the output time of the high level in each switching cycle to increase the duty ratio of the control signal. D, and output a control signal for increasing the duty ratio D to the converter.
  • the converter is a switching DC boost circuit, and the switching DC boost circuit controls the conduction of the switching tube by the duty ratio of the input control signal to achieve the control output voltage.
  • the relationship between the output voltage v out and the input voltage v in is In the case where the control to maintain the output voltage v OUT load constant, increasing the duty cycle of the control signal D, may reduce the input voltage v battery string circuit provided in.
  • the output current of the battery string circuit increases, and at this time, the photovoltaic cell string 2 to the photovoltaic cell string m
  • the output current is the current maximum value I sc , and the forward current of the photovoltaic cell string 1 increases, causing the reverse current of the photovoltaic cell string 1 to decrease until the reverse current of the photovoltaic cell string 1 is less than the short circuit current of the photovoltaic cell or 0. So far, it protects the photovoltaic cell string.
  • the photovoltaic system includes a plurality of photovoltaic cell strings, a converter, a controller, and a bus bar, and the plurality of photovoltaic cell strings includes at least one string group connected by two or three photovoltaic cells in series and connected to the current sensor.
  • At least one string group is connected in parallel and connected to the converter through a bus bar, and the converter is connected to the controller, and the controller is respectively connected with a current sensor in each of the at least one string group, and the current sensor is used for detecting each string group Total current, and report to the controller whether there is reverse current in each string group, and the controller is used to receive the target in at least one string group reported by the current sensor
  • the control signal output to the converter is adjusted, and the converter is used to reduce the system voltage between the bus lines according to the adjusted control signal to reduce the reverse current in the target string group, thereby providing not only Photovoltaic cell protection and reduced equipment costs.
  • the program may be stored in a computer readable storage medium, and the storage medium may include: Flash disk, read-only memory (English: Read-Only Memory, referred to as: ROM), random accessor (English: Random Access Memory, referred to as: RAM), disk or optical disk.
  • ROM Read-Only Memory
  • RAM Random Access Memory

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Photovoltaic Devices (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

一种光伏系统，包括：多个光伏电池串、变换器、控制器以及母线，该多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，该至少一个串组并联后通过母线连接到变换器，控制器分别与该至少一个串组中的每个串组中的电流传感器连接，电流传感器用于检测每个串组的总电流，并向控制器上报每个串组中是否存在反向电流，控制器用于当接收到电流传感器上报的至少一个串组中的目标串组存在反向电流时，调整输出到变换器的控制信号，变换器用于根据经过调整的控制信号，降低母线之间的系统电压以减小目标串组中的反向电流，不仅可以提供光伏电池保护，而且减少了设备成本。

Description

一种光伏系统 技术领域
本发明涉及电子技术领域，尤其涉及一种光伏系统。
背景技术
在光伏逆变器应用场景中，光伏电池通过串、并联方式进行连接，以向负载提供输出电压和输出电流。但是，如果其中一个光伏电池串短路，可能导致其他光伏电池串向该短路的光伏电池串灌入反向电流，若反向电流大于光伏电池的短路电流，则可能导致该出现故障的光伏电池串烧毁，在严重情况下甚至产生火灾，因此针对光伏电池串需要增加相应的保护措施，避免发生重大事故。
在现有技术方案中，各个光伏电池串与一个电流传感器连接，每个电流传感器实时检测各个光伏电池串的电流，当电流传感器检测某个光伏电池串存在反向电流时，将该反向电流上报到控制器，控制器控制变换器降低该光伏电池串的反向电流，起到保护光伏电池的作用。但是，在该技术方案中各个光伏电池串都需要连接一个电流传感器，导致增加了设备成本。
发明内容
本发明提供一种光伏系统。不仅可以提供光伏电池保护，而且减少了设备成本。
本发明第一方面提供了一种光伏电池保护电路，包括：多个光伏电池串、变换器、控制器以及母线，所述多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，所述至少一个串组并联后通过所述母线连接到所述变换器，所述变换器与所述控制器连接，所述控制器分别与所述至少一个串组中的每个串组中的电流传感器连接，所述电流传感器用 于检测所述每个串组的总电流，并向所述控制器上报所述每个串组中是否存在反向电流，所述控制器用于当接收到所述电流传感器上报的所述至少一个串组中的目标串组存在反向电流时，调整输出到所述变换器的控制信号，所述变换器用于根据经过调整的所述控制信号，降低所述母线之间的系统电压以减小所述目标串组中的反向电流。
在第一方面的第一种可能的实现方式中，所述多个光伏电池串还包括由一个光伏电池串与电流传感器连接的串组，所述由一个光伏电池串与电流传感器连接的串组与所述至少一个由两个或三个光伏电池串并联后连接电流传感器的串组并联后通过所述母线连接到所述变换器，所述由一个光伏电池串与电流传感器连接的串组中的电流传感器连接到所述控制器。
在第一方面的第二种可能的实现方式中，所述变换器包括开关管、第一电容、电感以及第一二极管，其中：
所述电感的一端与所述变换器的输入端连接，所述电感的另一端分别与所述开关管的集电极以及所述第一二极管的正极连接，所述第一二极管的负极与所述第一电容的一端连接，所述第一电容的另一端分别与所述开关管的发射级连接以及所述变换器的输出端连接。
在第一方面的第三种可能的实现方式中，所述控制器包括处理器以及驱动器，其中：
所述处理器，用于判断所述目标串组中的反向电流是否大于所述预设阈值；
所述驱动器，与所述处理器连接，用于当所述处理器判断得到所述目标串组中的反向电流大于所述预设阈值时，调整输出到所述变换器的控制信号。
结合第一方面的第三种可能的实现方式，在第一方面的第四种可能的实现方式中，所述控制器还包括模数转换器，所述模数转换器与所述处理器连接，用于将所述电流传感器上报的反向电流的模拟信号转化为反向电流的数字信号，并将所述反向电流的数字信号输出到所述处理器。
结合第一方面的第二种可能的实现方式，在第一方面的第五种可能的实现方式中，所述变换器还包括第二电容，所述第二电容的一端与所述电感的一端连接，所述第二电容的另一端与所述开关管的发射级连接，所述第二电容用于对所述输入电压进行滤波处理。
实施本发明，光伏系统包括多个光伏电池串、变换器、控制器以及母线，多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，至少一个串组并联后通过母线连接到变换器，变换器与控制器连接，控制器分别与至少一个串组中的每个串组中的电流传感器连接，电流传感器用于检测每个串组的总电流，并向控制器上报每个串组中是否存在反向电流，控制器用于当接收到电流传感器上报的至少一个串组中的目标串组存在反向电流时，调整输出到变换器的控制信号，变换器用于根据经过调整的控制信号，降低母线之间的系统电压以减小目标串组中的反向电流，从而不仅可以提供光伏电池保护，而且减少了设备成本。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明实施例提出的一种光伏系统的结构示意图；
图2是本发明实施例提出的一种光伏系统中的变换器的结构示意图；
图3是本发明实施例提出的一种光伏系统中的控制器的结构示意图；
图4是光伏电池串的工作V-I曲线图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行 清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
请参考图1，图1是本发明实施例提出的一种光伏系统的结构示意图。如图1所示，光伏系统包括多个光伏电池串、变换器、控制器以及母线，多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，所述至少一个串组并联后通过母线(1，2)连接到变换器，变换器与控制器连接，控制器分别与所述至少一个串组中的每个串组中的电流传感器连接，电流传感器用于检测所述每个串组的总电流，并向控制器上报所述每个串组中是否存在反向电流，控制器用于当接收到所述电流传感器上报的所述至少一个串组中的目标串组存在反向电流时，调整输出到所述变换器的控制信号，变换器用于根据经过调整的所述控制信号，降低母线(1，2)之间的系统电压以减小目标串组中的反向电流。
可选的，多个光伏电池串还包括由一个光伏电池串与电流传感器连接的串组，所述由一个光伏电池串与电流传感器连接的串组与所述至少一个由两个或三个光伏电池串并联后连接电流传感器的串组并联后通过母线(1，2)连接到变换器，所述由一个光伏电池串与电流传感器连接的串组中的电流传感器连接到控制器。
可选的，如图2所示，变换器包括开关管、第一电容C1、电感L以及第一二极管D1，其中：电感L的一端与变换器的输入端连接，电感L的另一端分别与开关管的集电极以及第一二极管D1的正极连接，第一二极管D1的负极与第一电容C1的一端连接，第一电容C1的另一端分别与开关管的发射级连接以及变换器的输出端极连接。
进一步可选的，变换器还包括第二电容C2，第二电容C2的一端与电感L的一端连接，第二电容C2的另一端与开关管的发射级连接，第二电容C2用于对输入电压进行滤波处理。
可选的，如图3所示，控制器包括处理器302以及驱动器303，其中：
所述处理器302，用于判断所述目标串组中的反向电流是否大于所述预设阈值。
所述驱动器303，与所述处理器连接，用于当所述处理器判断得到所述目标串组中的反向电流大于所述预设阈值时，调整输出到所述变换器的控制信号。
进一步可选的，控制器还包括模数转换器301，模数转换器301与处理器连接302，用于将所述电流传感器上报的反向电流的模拟信号转化为反向电流的数字信号，并将所述反向电流的数字信号输出到所述处理器。
在本发明实施例中，当存在反向电流的串组包括一个光伏电池串时，控制器调整输出到变换器的控制信号，变换器根据经过调整的所述控制信号，降低所述母线(1，2)之间的系统电压，将该串组的反向电流减小到小于光伏电池的短路电流。当存在反向电流的串组包括二个或三个光伏电池串时，控制器调整输出到变换器的控制信号，变换器根据经过调整的所述控制信号，降低所述母线(1，2)之间的系统电压，将所述串组的反向电流减小到0。
例如：如图1所示，光伏系统包括n个串组，n个串组包括m个光伏电池串，第一串组中包括1个光伏电池串，第二串组中包括3个光伏电池串，第n串组中包括2个光伏电池串。当第一串组中的光伏电池串1出现短路时，其他光伏电池串2～光伏电池串m的输出电流均为电流最大值Isc，导致光伏电池串2～光伏电池串m向光伏电池串1灌入反向电流(m-1)Isc，电流传感器T1检测到第一串组出现反向电流且反向电流的电流值为(m-1)Isc。或当第二串组中的光伏电池串1出现短路时，光伏电池串2～光伏电池串m的输出电流均为电流最大值Isc，导致光伏电池串2～光伏电池串m向光伏电池串1灌入反向电流(m-1)Isc，此时电流传感器T2检测到第二串组出现反向电流 且反向电流的电流值为(m-3)Isc。或当第n串组中的光伏电池串1出现短路时，光伏电池串2～光伏电池串m的输出电流均为电流最大值Isc，导致光伏电池串2～光伏电池串m向光伏电池串1灌入反向电流(m-1)Isc，此时电流传感器Tn检测到第二串组出现反向电流且反向电流的电流值为(m-2)Isc。
此时，电流传感器将上述反向电流上报的控制器，当控制器判断该反向电流大于预设阈值时，控制器增加每个开关周期中高电平的输出时间以增加控制信号的占空比D，并将增加占空比D的控制信号输出到变换器。如图2所示，变换器为开关直流升压电路，该开关直流升压电路通过输入控制信号的占空比控制开关管的导通从而达到控制输出电压。在开关直流升压电路中，输出电压vout与输入电压vin的关系为
Figure PCTCN2015086244-appb-000001
在控制负载保持输出电压vout恒定的情况下，增加控制信号的占空比D，可以减小电池组串电路提供的输入电压vin。根据如图4所示的光伏电池串的工作V-I曲线，当电池组串电路提供的输入电压vin减小时，电池组串电路的输出电流增大，此时光伏电池串2～光伏电池串m的输出电流均为电流最大值Isc，光伏电池串1的正向电流增加，导致光伏电池串1的反向电流减小，直到光伏电池串1的反向电流小于光伏电池的短路电流或者0为止，从而起到保护光伏电池串作用。
在本发明实施例中，光伏系统包括多个光伏电池串、变换器、控制器以及母线，多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，至少一个串组并联后通过母线连接到变换器，变换器与控制器连接，控制器分别与至少一个串组中的每个串组中的电流传感器连接，电流传感器用于检测每个串组的总电流，并向控制器上报每个串组中是否存在反向电流，控制器用于当接收到电流传感器上报的至少一个串组中的目标 串组存在反向电流时，调整输出到变换器的控制信号，变换器用于根据经过调整的控制信号，降低母线之间的系统电压以减小目标串组中的反向电流，从而不仅可以提供光伏电池保护，而且减少了设备成本。
需要说明的是，对于前述的各个方法实施例，为了简单描述，故将其都表述为一系列的动作组合，但是本领域技术人员应该知悉，本发明并不受所描述的动作顺序的限制，因为依据本发明，某一些步骤可以采用其他顺序或者同时进行。其次，本领域技术人员也应该知悉，说明书中所描述的实施例均属于优选实施例，所涉及的动作和模块并不一定是本发明所必须的。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详细描述的部分，可以参见其他实施例的相关描述。
本领域普通技术人员可以理解上述实施例的各种方法中的全部或部分步骤是可以通过程序来指令相关的硬件来完成，该程序可以存储于一计算机可读存储介质中，存储介质可以包括：闪存盘、只读存储器(英文：Read-Only Memory，简称：ROM)、随机存取器(英文：Random Access Memory，简称：RAM)、磁盘或光盘等。
以上对本发明实施例所提供的内容下载方法及相关设备、系统进行了详细介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。

Claims (6)

  1. 一种光伏系统，其特征在于，所述光伏系统包括多个光伏电池串、变换器、控制器以及母线，所述多个光伏电池串包括至少一个由两个或三个光伏电池串并联后连接电流传感器的串组，所述至少一个串组并联后通过所述母线连接到所述变换器，所述变换器与所述控制器连接，所述控制器分别与所述至少一个串组中的每个串组中的电流传感器连接，所述电流传感器用于检测所述每个串组的总电流，并向所述控制器上报所述每个串组中是否存在反向电流，所述控制器用于当接收到所述电流传感器上报的所述至少一个串组中的目标串组存在反向电流时，调整输出到所述变换器的控制信号，所述变换器用于根据经过调整的所述控制信号，降低所述母线之间的系统电压以减小所述目标串组中的反向电流。
  2. 如权利要求1所述的光伏系统，其特征在于，所述多个光伏电池串还包括由一个光伏电池串与电流传感器连接的串组，所述由一个光伏电池串与电流传感器连接的串组与所述至少一个由两个或三个光伏电池串并联后连接电流传感器的串组并联后通过所述母线连接到所述变换器，所述由一个光伏电池串与电流传感器连接的串组中的电流传感器连接到所述控制器。
  3. 如权利要求1或2所述的光伏系统，其特征在于，所述变换器包括开关管、第一电容、电感以及第一二极管，其中：
    所述电感的一端与所述变换器的输入端连接，所述电感的另一端分别与所述开关管的集电极以及所述第一二极管的正极连接，所述第一二极管的负极与所述第一电容的一端连接，所述第一电容的另一端分别与所述开关管的发射级连接以及所述变换器的输出端连接。
  4. 如权利要求1或2所述的光伏系统，其特征在于，所述控制器包括处理器以及驱动器，其中：
    所述处理器，用于判断所述目标串组中的反向电流是否大于所述预设阈值；
    所述驱动器，与所述处理器连接，用于当所述处理器判断得到所述目标串组中的反向电流大于所述预设阈值时，调整输出到所述变换器的控制信号。
  5. 如权利要求4所述的光伏系统，其特征在于，所述控制器还包括模数转换器，所述模数转换器与所述处理器连接，用于将所述电流传感器上报的反向电流的模拟信号转化为反向电流的数字信号，并将所述反向电流的数字信号输出到所述处理器。
  6. 如权利要求3所述的光伏系统，其特征在于，所述变换器还包括第二电容，所述第二电容的一端与所述电感的一端连接，所述第二电容的另一端与所述开关管的发射级连接，所述第二电容用于对所述输入电压进行滤波处理。
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CN105827179A (zh) 2016-08-03
EP3174196A4 (en) 2017-07-26

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