WO2022052646A1 - 一种直流汇流箱、逆变器、光伏系统及保护方法 - Google Patents

一种直流汇流箱、逆变器、光伏系统及保护方法 Download PDF

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Publication number
WO2022052646A1
WO2022052646A1 PCT/CN2021/107738 CN2021107738W WO2022052646A1 WO 2022052646 A1 WO2022052646 A1 WO 2022052646A1 CN 2021107738 W CN2021107738 W CN 2021107738W WO 2022052646 A1 WO2022052646 A1 WO 2022052646A1
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Prior art keywords
combiner box
output
circuit
input
negative
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Application number
PCT/CN2021/107738
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English (en)
French (fr)
Inventor
王晨
张彦忠
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华为数字能源技术有限公司
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Priority to EP21865702.1A priority Critical patent/EP4195483A4/en
Publication of WO2022052646A1 publication Critical patent/WO2022052646A1/zh
Priority to US18/173,762 priority patent/US20230208354A1/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
    • 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
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • 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
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • 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
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/34—Electrical components comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
    • 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—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
    • 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
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
    • 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 application relates to the technical field of photovoltaic power generation, and in particular, to a DC combiner box, an inverter, a photovoltaic system and a protection method.
  • FIG. 1 the figure is a schematic diagram of a photovoltaic system provided in the prior art.
  • the DC combiner box is hereinafter referred to as the combiner box 100 for short.
  • the output end of the combiner box 100 is connected to the input end of the inverter 200 .
  • the multiple combiner boxes 100 are all connected to the input ends of the inverter 200 , that is, the output ends of the multiple combiner boxes 100 are connected in parallel with the input ends of the inverter 200 .
  • Some combiner boxes have the function of Maximum Power Point Tracking (MPPT, Maximum Power Point Tracking).
  • MPPT Maximum Power Point Tracking
  • DC/DC converters inside the combiner boxes which are generally boosted DC/DC converters.
  • the DC converter is introduced as an example of Boost.
  • the combiner box 100 is generally far away from the inverter 200, and the two are connected by positive and negative cables.
  • the insulation of the positive and negative cables is easily damaged and short-circuited or the positive and negative cables of the combiner box are easily damaged.
  • the positive and negative connections are reversed when connecting to the inverter.
  • the dotted line in Figure 1 represents the current path when the positive and negative cables of the combiner box are reversely connected.
  • the present application provides a DC combiner box, an inverter, a photovoltaic system and a protection method, which can protect the combiner box and the cables in time when the cables are damaged and short-circuited or the positive and negative cables are reversed. .
  • the present application provides a DC combiner box, the combiner box is connected between a photovoltaic array and an inverter, and a switching device is connected in parallel between the positive input end and the negative output end of the DC combiner box, and the switching device may be included in the combiner box. , and may be additionally added, which is not limited in the embodiments of the present application.
  • the controller determines that the output terminal of the DC combiner box is short-circuited or reversely connected, the controller controls the switching device to close, and the switching device, the positive input terminal and the negative input terminal form a closed loop.
  • the specific controller can collect at least one parameter among the input parameters and output parameters of the combiner box according to the sampling circuit, and determine whether a short circuit occurs between the output positive cable and the output negative cable, or, the output positive cable and the output negative cable Whether the connection is reversed.
  • the positive input terminal and the negative input terminal are connected through the closed switching device, and the current path is from the positive input terminal of the combiner box through the closed switching device to the negative input terminal of the combiner box, forming a closed loop. Therefore, when the output end of the combiner box or the post-stage circuit of the output end is short-circuited, most of the short-circuit current passes through the closed switching device to form a backflow, thereby greatly reducing the output of the current generated at the input end of the combiner box from the output end of the combiner box, that is, Reduce the output current of the combiner box, so as to avoid the overcurrent burning of the output positive cable and the output negative cable of the combiner box when the output current of the combiner box is too large, that is, to protect the power cable from being burnt due to overcurrent.
  • the technical solution can also protect the combiner box when the output positive cable and the output negative cable are reversely connected.
  • the sampling circuit can collect output parameters of the combiner box, and can also collect input parameters of the combiner box, the output parameters can include output current and output voltage, and the input parameters can include input voltage and input current, that is, the sampling circuit can collect the output parameters of the combiner box At least one of the following parameters: output voltage of the combiner box, output current of the combiner box, input voltage of the combiner box and input current of said combiner box; controller, for the express drop in output voltage or input voltage, or, input current Or when the output current rises rapidly, determine that the output end of the combiner box is short-circuited or reversed.
  • the controller controls the switching device to close;
  • the at least one condition includes: the drop speed of the output voltage of the combiner box exceeds the first preset value, and the drop speed of the input voltage of the combiner box exceeds the second The preset value, the increasing speed of the output current of the combiner box exceeds the third preset value, and the increasing speed of the input current of the combiner box exceeds the fourth preset value.
  • the switching device is implemented by the main power tube in the DC/DC converter, that is, the main power tube is controlled to be closed by controlling the switching device to be closed.
  • the DC/DC converter converts the direct current output from the photovoltaic array and outputs it to the inverter; the switching device includes at least the main power tube in the DC/DC converter; the controller controls the main power tube in the DC/DC converter closed, so that the main power tube, the positive input terminal and the negative input terminal form a closed loop.
  • the voltage of the photovoltaic array can be lower than
  • the action of the main power tube is controlled only when the voltage value is preset, that is, the controller controls the DC/DC converter when at least one parameter satisfies the at least one condition and the input voltage of the DC/DC converter is less than the preset voltage value
  • the main power tube in is closed.
  • the DC/DC converter includes at least any one of the following: a two-level Boost circuit, a three-level Boost circuit, and a BuckBoost circuit.
  • the switching device when the DC/DC converter includes a three-level boost circuit, the switching device includes at least two series-connected main power tubes in the three-level boost circuit, and the two series-connected main power tubes are connected to the positive input end and the negative input between the terminals; when at least one parameter satisfies the at least one condition and the input voltage of the DC/DC converter is less than a preset voltage value, the controller controls both the two main power tubes connected in series to be closed.
  • the combiner box includes a DC/DC converter and other switches connected in parallel between its positive and negative input ends
  • the controller controls the main power tube in the DC/DC converter to close
  • the control and DC/DC converters are closed.
  • the parallel switch of the main power tube in the DC converter is also closed, which can increase the shunt branch, thereby shunt the current at the output end to a greater extent and reduce the current flowing to the output end of the combiner box.
  • the output switch at the output end of the combiner box is closed; since the current at the output end of the combiner box has already It is shunted and reduced. Therefore, when the output switch is disconnected at this time, it is easy to disconnect, and it will not be stuck and cannot be disconnected because the current is too large.
  • the output switch is connected in series with the positive output terminal of the combiner box and/or in series with the negative output terminal of the combiner box.
  • the combiner box includes at least two DC/DC converters, that is, includes a plurality of DC/DC converters; the output ends of the at least two DC/DC converters are connected in parallel; The input terminals are respectively connected to different PV strings, and all PV strings form a PV array.
  • the embodiment of the present application also provides an inverter, including: a DC/DC conversion circuit, an inverter circuit, a sampling circuit and a controller; an input end of the DC/DC conversion circuit is used to connect a photovoltaic array; the DC/DC conversion circuit converts the The DC power of the photovoltaic array is converted and output to the inverter circuit; the inverter circuit converts the DC power output by the DC/DC conversion circuit into AC power for output; the sampling circuit is used to collect the input parameters of the DC/DC conversion circuit and At least one of the output parameters.
  • the controller determines, according to at least one parameter, that when a short circuit occurs at the output end of the DC/DC conversion circuit, the inverter circuit itself, or the output end of the inverter circuit, it controls the main power tube of the DC/DC conversion circuit to close, so that the main power tube and the inverter circuit are closed.
  • the input end of the DC/DC conversion circuit forms a closed loop.
  • At least one parameter includes: the output voltage of the DC/DC conversion circuit, the output current of the DC/DC conversion circuit, the input voltage of the DC/DC conversion circuit, and the voltage of the DC/DC conversion circuit. an input current; a controller configured to control the switching device to close when the at least one parameter satisfies at least one of the following conditions, the at least one condition comprising: the drop speed of the output voltage of the DC/DC conversion circuit exceeds The fifth preset value, the falling speed of the input voltage of the DC/DC conversion circuit exceeds the sixth preset value, the increasing speed of the output current of the DC/DC conversion circuit exceeds the seventh preset value, the DC/DC conversion circuit The increasing speed of the input current of the DC conversion circuit exceeds the eighth preset value.
  • Embodiments of the present application further provide a photovoltaic system, including: a photovoltaic array and photovoltaic equipment, where the photovoltaic equipment is the above-mentioned combiner box or the above-mentioned inverter; and the input end of the photovoltaic equipment is used for connecting the photovoltaic array.
  • the photovoltaic system may include multiple combiner boxes, and the output ends of the multiple combiner boxes may be connected in parallel; that is, there are at least two combiner boxes, and the output ends of the two combiner boxes are connected to the the input of the inverter.
  • the photovoltaic device in the photovoltaic system is an inverter
  • the inverter since the inverter includes a DC/DC conversion circuit, the main power tube in the DC/DC conversion circuit is connected in parallel with the positive input terminal and the negative terminal of the photovoltaic device. Therefore, when a short circuit or reverse connection occurs, controlling the main power tube to close can realize the protection of the output terminal when the short circuit or reverse connection occurs.
  • the embodiment of the present application also provides a protection method for a DC combiner box, which is applied to the combiner box described above; the method includes: collecting at least one parameter of an input parameter and an output parameter of the combiner box; parameter, determine that a short circuit occurs between the output positive cable and the output negative cable, or, when the output positive cable and the output negative cable are reversely connected, control the switching device to close, A closed loop is formed between the switching device, the positive input terminal and the negative input terminal.
  • controlling the switching device to close which specifically includes: when the at least one parameter satisfies at least one of the following conditions, controlling the switching device to close; the at least one condition includes: the drop speed of the output voltage of the combiner box exceeds The first preset value, the falling speed of the input voltage of the combiner box exceeds the second preset value, the increasing speed of the output current of the combiner box exceeds the third preset value, the increasing speed of the input current of the combiner box A fourth preset value is exceeded; the at least one parameter includes: the output voltage of the combiner box, the output current of the combiner box, the input voltage of the combiner box, and the input current of the combiner box.
  • the switching device when the combiner box includes a DC/DC converter, the switching device includes at least a main power tube in the DC/DC converter; the controlling the switching device to be closed specifically includes: when the switching device is closed.
  • the main power tube in the DC/DC converter is controlled to be closed.
  • the combiner box further comprises: an output switch; the output switch is connected in series with the positive output end of the combiner box and/or connected in series with the negative output end of the combiner box; when controlling the DC/DC converter After the main power tube in the device is closed, the method further includes: controlling the output switch of the combiner box to be disconnected.
  • the method detects at least one of the input parameters and output parameters of the combiner box, and determines by at least one parameter that a short circuit occurs between the positive and negative output cables of the combiner box, or when the positive and negative output cables are reversed, control the The switching device between the positive input end and the negative input end of the combiner box is closed, and the current path is from the positive input end of the combiner box to the negative input end of the combiner box through the closed switch device, forming a closed loop.
  • the closed switch device In this way, when a short circuit occurs, most of the short-circuit current passes through the closed switch device to form a backflow, which greatly reduces the current output from the combiner box. Therefore, it can avoid overcurrent burning of the power cable when the output current of the combiner box is too large, or When the output positive and negative cables are reversely connected, the combiner box will be damaged.
  • the solution detects at least one of the input parameters and output parameters of the combiner box, and determines by at least one parameter that a short circuit occurs between the output positive cable and the output negative cable of the combiner box, or the output positive cable and the output negative cable are short-circuited.
  • the controller is used to control the switching device between the positive input terminal and the negative input terminal of the combiner box to close. Since the switching device is connected in parallel between the positive input terminal and the negative input terminal of the combiner box, the switching device When closed, the positive input terminal and the negative input terminal are connected through the closed switching device, and the current path is from the positive input terminal of the combiner box to the negative input terminal of the combiner box through the closed switching device, forming a closed loop.
  • the technical solution can also protect the combiner box when the output positive cable and the output negative cable are reversely connected.
  • FIG. 1 is a schematic diagram of a photovoltaic system provided by the prior art
  • FIG. 2 is a schematic diagram of a DC combiner box provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a combiner box including a two-level boost circuit provided by an embodiment of the present application
  • FIG. 4 is a schematic diagram of a combiner box including a three-level boost circuit provided by an embodiment of the present application
  • FIG. 5 is a schematic diagram of a simple combiner box provided by an embodiment of the present application.
  • FIG. 6 is a schematic diagram of an inverter provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application.
  • FIG. 8 is a flowchart of a method for protecting a DC combiner box according to an embodiment of the present application.
  • a combiner box is a kind of Commonly used equipment, the input end of the combiner box is generally connected to the photovoltaic array. In order to provide power generation capacity, the combiner box needs to combine the energy of multiple photovoltaic strings. Since the output of the photovoltaic array is direct current, the combiner box is also called DC confluence. Of course, an AC combiner box may also exist on the inverter side, and the DC combiner box is specifically introduced in the embodiments of the present application.
  • the output end of the DC combiner box is connected to the inverter, and the inverter inverts the DC power into AC power and feeds it back to the AC grid.
  • the output terminal of the combiner box includes a positive output terminal and a negative output terminal.
  • the positive output terminal of the combiner box is connected to the positive input terminal of the inverter through the output positive cable, and the negative output terminal of the combiner box is connected through the output negative cable.
  • the negative input of the inverter is connected to the positive input terminal of the inverter through the output positive cable.
  • the technical solution provided by the embodiment of the present application is that when a short circuit occurs between the output positive cable and the output negative cable of the combiner box, or the output positive and negative cables are reversely connected, the controller controls the positive input end of the combiner box to be connected in parallel
  • the switching device between the junction box and the negative input terminal is closed, so that the positive input terminal, the negative input terminal and the closed switching device of the combiner box form a closed loop, that is, the switching device is used to provide a current path when the output terminal of the combiner box is short-circuited or reversed.
  • the combiner box so as to shunt the output current of the combiner box, reduce the current at the output end of the combiner box, and avoid excessive short-circuit current to cause damage to the output positive cable and the output negative cable, that is, to protect the output positive cable of the combiner box and the output negative cable.
  • the cable in addition, protects the combiner box from being damaged when the output positive cable and the output negative cable of the combiner box are reversed.
  • the technical solutions provided in the embodiments of this application are applicable to common combiner boxes, that is, the combiner box does not include a DC/DC converter, such as a combiner box without a boost function, when applying this technical solution to a common combiner box, as long as the A switching device may be connected in parallel between the positive input terminal and the negative input terminal. When there is no switching device in the combiner box, such a switching device can be added.
  • the technical solutions provided in the embodiments of the present application are also applicable to combiner boxes with transformer functions, such as boost function, step-down function, boost-voltage function, etc., that is, the inside of the combiner box may include a DC/DC converter, such as a combiner box The inside of the box includes a boost converter.
  • the DC/DC converter has its own switching device, that is, the main power tube of the DC/DC converter is used as a switching device to short-circuit between the output positive cable and the output negative cable of the combiner box. Or when the output positive cable and the output negative cable are reversely connected, the combiner box can be protected by controlling the closing of the main power tube in the DC/DC converter.
  • the switching devices in the embodiments of the present application include but are not limited to the following devices: IGBTs, MOSFETs, triodes, relays, circuit breakers and other switching devices with breaking capability.
  • FIG. 2 this figure is a schematic diagram of a DC combiner box provided by an embodiment of the present application.
  • the output end of the DC combiner box 100 provided in this embodiment is connected to the input end of the inverter 200 , that is, the combiner box on the DC side.
  • the DC combiner box is simply referred to as a combiner box.
  • the input end of the combiner box 100 is used to connect the photovoltaic array PV.
  • the photovoltaic array PV may include multiple photovoltaic strings, and the multiple photovoltaic strings may be connected in parallel.
  • each photovoltaic string includes multiple photovoltaic panels connected in series.
  • the positive output terminal of the combiner box 100 is used to connect the positive input terminal of the inverter 200 through the output positive cable
  • the negative output terminal of the combiner box 100 is used to connect the negative input terminal of the inverter 200 through the output negative cable.
  • the positive input end of the combiner box 100 is connected to the first end of the photovoltaic array PV, and the negative input end of the combiner box 100 is connected to the second end of the photovoltaic array PV.
  • the combiner box includes: a sampling circuit 101, a controller 102 and a switching device (not shown in the figure).
  • a switching device is connected between the positive input terminal and the negative input terminal of the combiner box.
  • Each combiner box may include a controller 102, particularly a combiner box with a Maximum Power Point Tracking (MPPT) function.
  • MPPT Maximum Power Point Tracking
  • a sampling circuit 101 for collecting at least one parameter of the input parameter and the output parameter of the combiner box 100;
  • the controller 102 is configured to determine, according to the at least one parameter, that a short circuit occurs between the output positive cable and the output negative cable of the combiner box, or, the output positive cable and the output
  • the control switch device is closed, so that the positive input end of the combiner box, the negative input end of the combiner box and the switching device form a closed loop, that is, in the case of a short circuit, the current passes through the positive input end of the combiner box.
  • the switching device reaches the negative input of the combiner box to form a return flow.
  • the input parameters of the combiner box can be collected to determine whether the output terminal of the combiner box and the subsequent stage circuit of the output terminal are short-circuited or reversed; the output terminal of the combiner box can also be judged by collecting the output parameters of the combiner box. And whether the post-stage circuit at the output end is short-circuited, or whether the connection is reversed.
  • the above parameters include voltage or current.
  • the sampling circuit when the sampling circuit collects the input parameters of the combiner box, it can collect the input voltage of the combiner box or the input current of the combiner box;
  • the sampling circuit collects the output parameters of the combiner box, it can collect the output voltage of the combiner box or the output current of the combiner box.
  • the controller is sampling When at least one parameter collected by the circuit satisfies at least one of the following conditions, it is determined that the output end of the combiner box is short-circuited or reversed, and the controller controls the switching device to close, and the at least one condition includes: the output voltage of the combiner box drops.
  • the speed exceeds the first preset value, the falling speed of the input voltage of the combiner box exceeds the second preset value, the increasing speed of the output current of the combiner box exceeds the third preset value, the input current of the combiner box Increase the speed beyond the fourth preset value.
  • the decreasing speed and increasing speed of each of the above parameters can be obtained through the parameter change slope.
  • the output voltage of the combiner box is collected, and when the corresponding slope of the output voltage drops exceeds the first preset value, it is considered that the output voltage of the combiner box drops rapidly, and it is determined that there is a short circuit between the positive and negative output cables of the combiner box.
  • the judgment methods of other parameters are the same, and will not be repeated here.
  • the solution detects at least one of the input parameters and output parameters of the combiner box, and determines by at least one parameter that a short circuit occurs between the output positive cable and the output negative cable of the combiner box, or the output positive cable and the output negative cable are short-circuited.
  • the switch device between the positive input terminal and the negative input terminal of the control combiner box is closed. Since the switch device is connected in parallel between the positive input terminal and the negative input terminal of the combiner box, when the switch device is closed, the The current path is from the positive input end of the combiner box through the closed switching device to the negative input end of the combiner box, which forms a closed loop.
  • the following takes the DC/DC converter included in the combiner box as an example to introduce.
  • the DC/DC converter is used to convert the direct current output from the photovoltaic array and output it to the inverter; specifically, the DC/DC converter is used as a boost converter.
  • the switch device in the combiner box includes at least the main power tube in the DC/DC converter;
  • the controller specifically controls the main power tube in the DC/DC converter to close, so that the main power tube, the positive The input terminal and the negative input terminal form a closed loop. That is, the controller can control the main power tube by outputting a pulse drive signal to the main power tube in the DC/DC converter, such as outputting a PWM signal.
  • the high level of the PWM signal corresponds to the main power tube being closed, and the PWM signal The low level corresponds to the disconnection of the main power tube.
  • the specific topology form of the DC/DC converter is not specifically limited in the embodiments of the present application, for example, it includes at least any one of the following: a two-level Boost circuit, a three-level Boost circuit, and a BuckBoost circuit.
  • the following takes the DC/DC converter in the combiner box as a two-level boost circuit as an example to introduce.
  • the combiner box includes at least two DC/DC converters
  • the output ends of the two DC/DC converters are connected in parallel;
  • the input ends of the two DC/DC converters are connected to different photovoltaic strings, and all the photovoltaic strings form the photovoltaic array.
  • FIG. 3 is a schematic diagram of a combiner box including a two-level boost circuit according to an embodiment of the present application.
  • the photovoltaic system includes n combiner boxes, that is, the combiner box 100 to the combiner box 10n.
  • n can be an integer greater than or equal to 1.
  • Each combiner box includes m DC/DC converters as an example, where m may be an integer greater than or equal to 2.
  • the output ends of the m DC/DC converters are connected in parallel, and the output ends of the n combiner boxes 100 are all connected to the input ends of the inverter 200 .
  • the external of 200 realizes parallel connection.
  • each combiner box 100 includes a controller 102, that is, the controller 102 of each combiner box 100 independently completes the control of its corresponding combiner box.
  • the combiner box 100 includes m boost circuits, wherein the main power tube of the first boost circuit is Q1_1 and the diode is D1_1; the main power tube of the mth boost circuit is Qm_1 and the diode is Dm_1.
  • the outputs of m boost circuits are connected in parallel, that is, a common DC bus.
  • the DC bus corresponding to the first combiner box 100 is BUS1
  • the DC bus corresponding to the nth combiner box 10n is BUSn.
  • the output switch of the first combiner box 100 is K1
  • the output switch of the nth combiner box 10n is Kn.
  • the output switch can only be connected in series with the positive output terminal, or only in series with the negative output terminal, or as shown in the figure, both the negative output terminal and the positive output terminal of the combiner box can be connected in series with the output switch.
  • the sampling circuit is not shown in FIG. 3 , but only the controller 102 and the power supply unit 103 are shown. Taking the first combiner box 100 as an example, the controller 102 and the power supply unit 103 are included.
  • the power supply unit 103 is used to supply power to the sampling circuit and the controller 102 .
  • the power source of the power supply unit 103 may be a DC bus, a battery panel string, or other independent power sources, which are not specifically limited herein.
  • the positive output end of the combiner box 100 is connected to the negative input end of the inverter through the output positive cable P1, and the combiner The negative output terminal of the box 100 is connected to the positive input terminal of the inverter through the output positive cable N1.
  • the arrow in the figure shows the current direction when the output positive cable P1 and the output negative cable N1 of the combiner box 100 are reversely connected.
  • the positive output end of the combiner box 100 is connected to the positive input end of the inverter through the output positive cable P1, and the combiner box 100
  • the negative output terminal of the inverter is connected to the negative input terminal of the inverter through the output positive cable N1.
  • a switch S1 is provided inside the inverter 200 for safety, that is, the output end of the combiner box is connected to the input end of the inverter through the switch S1.
  • the combiner box and the inverter can be disconnected by disconnecting S1. connection to the input of the device.
  • the main power tube Q1 that controls the Boost circuit is closed. After Q1 is closed, Q1 is equivalent to shunt the current sent to the combiner box in parallel with D1, and The conduction voltage drop of D1 is relatively large, so most of the short-circuit current of the battery string is backflowed from Q1, and the current flowing through D1 is small. Therefore, most of the current will not flow out from the output end of the combiner box, so It can avoid the overcurrent burning of the power cable caused by the excessive output current of the combiner box, or the damage caused by the reverse connection of the positive and negative output terminals of the combiner box.
  • the combiner box in Figure 3 includes multiple boost circuits in parallel, and the input end of each boost circuit corresponds to an independent battery panel string. Or if the input current rises rapidly, the main power tube in the boost circuit is controlled to be closed, thereby protecting the corresponding combiner box and cables.
  • the main power tubes Q1-Qm that control the Boost circuit are closed. After Q1-Qm is closed, Q1-Qm is equivalent to parallel shunt with D1-Dm.
  • the current of the combiner box, and the on-state voltage drop of D1-Dm is relatively large, so most of the short-circuit current of the panel string flows back from Q1-Qm, and the current flowing through D1-Dm is small, therefore, most of The current will not flow out from the output end of the combiner box, which can avoid the overcurrent burning of the power cable due to the excessive output current of the combiner box, or the damage caused by the reverse connection of the positive and negative output ends of the combiner box.
  • all switch tubes of all combiner boxes connected to the fault are controlled to be closed, so as to prevent the current of other combiner boxes from flowing through the short-circuit place and causing burning.
  • an input filter capacitor is connected between the input positive terminal and the input negative terminal of the battery panel string, when the voltage of the battery panel string is high, the main power tube is controlled to be turned on, the input filter capacitor is discharged, and the main power flows through The current of the tube will increase instantaneously, which may cause damage to Q1-Qm. Therefore, it is necessary to detect the input voltage of the DC/DC converter, that is, the PV voltage corresponding to the battery panel string, that is, the controller is specifically used when the DC/DC converter is used. When the input voltage of the converter is less than the preset voltage value, the main power tube in the DC/DC converter is controlled to be closed. At this time, the closing will not damage the main power tube due to overcurrent.
  • the specific preset voltage value can be based on the main power tube. The type and specific parameters of pressure resistance and current resistance are set.
  • the controller 102 is further configured to control the connection with the main power tube in the DC/DC converter when the main power tube in the DC/DC converter is closed.
  • the purpose of the parallel switching device of the main power tubes in the DC/DC converter is to further shunt the input current of the combiner box, reduce the current flowing into the output end of the combiner box, and thus better protect the combiner box and the inverter. The power cables between them can also better protect the combiner box.
  • the output end of the combiner box 100 further includes: an output switch K1; K1 has switch contacts connected in series on both the output positive cable and the output negative cable.
  • the output switch K1 is connected in series with the output end of the combiner box 100;
  • the controller 102 is further configured to control the output switch to be turned off when or after the switch device is turned on.
  • the function of K1 is mainly to disconnect the connection between the combiner box and the inverter.
  • the switching device can be controlled to be disconnected. At this time, since K1 is disconnected, the switching device is disconnected and will not cause damage to the subsequent circuit. For example, when K1 is disconnected, the DC bus has no electricity, and the switching device will automatically disconnect.
  • the combiner box provided in this embodiment includes a two-level boost circuit.
  • the main power tube in the two-level boost circuit is controlled to be closed, so as to shunt the current at the input end and make it pass through the main power tube.
  • the power tube forms a closed loop, reducing the current reaching the output end of the combiner box, thereby protecting the cables at the output end of the combiner box and protecting the combiner box from being damaged. Since the combiner box is equipped with a Boost circuit, the current shunt can be realized by controlling the main power tube in the Boost circuit, without adding a new hardware circuit, which saves costs and is easy to control.
  • the combiner box includes a two-level boost circuit, and the following is a three-level boost circuit with flying capacitors in the combiner box.
  • FIG. 4 is a schematic diagram of a combiner box including a three-level boost circuit according to an embodiment of the present application.
  • the switching device When the DC/DC converter includes a three-level boost circuit, the switching device includes at least two series-connected main power tubes in the three-level boost circuit, and the two series-connected main power tubes are connected to the between the positive input terminal and the negative input terminal;
  • the controller is specifically configured to control the two main power tubes connected in series when the at least one parameter satisfies the at least one condition and the input voltage of the DC/DC converter is less than a preset voltage value are closed.
  • the three-level Boost circuit includes two main power tubes, such as Q1_1_1 and Q2_1_1 in the first three-level Boost, and the two main power tubes in the mth three-level Boost are Q1_m_1 and Q2_m_1.
  • the two main power tubes are connected in series and connected in parallel to the input positive end and the input negative end of the three-level boost circuit.
  • a three-level boost circuit For a three-level boost circuit, it is determined that a short circuit occurs between the output positive cable and the output negative cable of the combiner box, or when the output positive cable and the output negative cable are reversely connected , it is necessary to control the two main power tubes connected in series in the three-level boost circuit to be closed, so that the main power tube and the input end of the combiner box form a closed loop, that is, Q1_1_1 and Q2_1_1 are both closed, and Q1_m_1 and Q2_m_1 are both closed. closure.
  • the three-level boost circuit also includes two diodes, as shown in the figure, D1_1_1 and D2_1_1, D1_m_1 and D2_m_1.
  • Q1_1_1 and Q2_1_1 are closed, most of the current of the battery string passes through Q1_1_1 and Q2_1_1, and because the conduction voltage drop of the diode is greater than that of the main power tube Therefore, the current reaching the output end of the combiner box through D1_1_1 and D2_1_1 is greatly reduced, so the power cable between the combiner box and the inverter can be protected, and the combiner box can be protected from damage.
  • the power supply unit 103 may supply power to the sampling circuit and the controller 102 .
  • control K1 When the control main power tube is closed, control K1 to open.
  • the current path indicated by the arrow direction in the figure is the path when the output positive cable and the output negative cable of the combiner box are reversely connected.
  • the combiner box provided in this embodiment includes a three-level boost circuit. Therefore, when the output end of the combiner box is short-circuited or reversed, the two main power tubes in the three-level boost circuit are controlled to be closed, so that the combiner box is divided.
  • the current at the input end reduces the current at the output end of the combiner box, thereby protecting the output positive cable and output negative cable of the combiner box, that is, protecting the power cable from being burnt by overcurrent, and when the output positive cable and the output negative cable are reversed , protect the combiner box from damage.
  • the combiner box comes with a three-level boost circuit, it can realize short-circuit or reverse connection protection by controlling the main power tube in the three-level boost circuit, and realize the shunt of short-circuit current without adding new hardware circuits, which is easy to implement. Cost savings and easy control.
  • the combiner box has a boost function.
  • the combiner box does not include a DC/DC converter, but only a simple combiner function, that is, a common combiner box.
  • the input positive terminal and the input negative terminal of the combiner box are connected in parallel. It is sufficient to have a switching device, and when there is no such switching device, such a switching device can be added.
  • this figure is a schematic diagram of a simple combiner box provided by an embodiment of the present application.
  • the combiner box 100 provided in this embodiment does not include a DC/DC converter, and the combiner box 100 only has a simple combining function, that is, the input currents of the various battery panel strings are aggregated and output to the inverter 200 .
  • each combiner box includes two circuits as an example.
  • the input terminals of the two circuits are respectively connected to the corresponding photovoltaic strings, and the output terminals of the two circuits are connected in parallel to realize the convergence.
  • This embodiment does not specifically limit the specific number of photovoltaic strings, nor does it limit the connection relationship and number of photovoltaic cells in the photovoltaic string, for example, a photovoltaic string in which a plurality of photovoltaic cells are connected in parallel may be included.
  • the switching devices Q1 and Q2 at the input end of each branch of the combiner box 100 can be newly added, or the existing switching devices can be used.
  • control Q1 and Q2 to close, so that the current flows.
  • the current reaching the output end of the combiner box 100 is reduced, the cables at the output end of the combiner box 100 are protected, and the combiner box is not damaged.
  • Q1 and Q2 are closed, K is controlled to be disconnected. Due to the short circuit of Q1 and Q2, the output voltage of the combiner box is clamped, that is, the output voltage of the combiner box is low, and K is easily disconnected. If the output voltage of the combiner box is high, there is a risk that K cannot be disconnected.
  • FIG. 5 is a schematic diagram showing that the positive output terminal and the negative output terminal of the combiner box 100 are reversely connected.
  • the combiner box provided in this embodiment may not have a DC/DC converter inside.
  • the switching devices connected in parallel with the positive input end and the negative input end of the combiner box can be controlled to close, and the positive input end can be controlled to close.
  • the terminal and the negative input terminal are connected through the closed switch device, and the current path is from the positive input terminal of the combiner box to the negative input terminal of the combiner box through the closed switch device, that is, a closed loop is formed.
  • the technical solution can also protect the combiner box when the output positive cable and the output negative cable are reversely connected.
  • the above embodiments describe the separate arrangement of the combiner box and the inverter.
  • the combiner box includes a DC/DC converter
  • the DC/DC converter is arranged inside the combiner box
  • the inverter is outside the combiner box.
  • the embodiment of the present application also provides an inverter, the inverter includes a DC/DC conversion circuit inside, that is, the inverter includes a DC/DC circuit and an inverter circuit, and the inverter has both a boosting function and a With inverter function.
  • FIG. 6 this figure is a schematic diagram of an inverter provided by an embodiment of the present application.
  • This embodiment provides an inverter 200, including: a DC/DC circuit 201, an inverter circuit 202, a sampling circuit and a controller (all not shown in the figure);
  • the input end of the DC/DC circuit 201 is used to connect to the photovoltaic array PV, and is used to convert the direct current of the photovoltaic array PV for output.
  • the photovoltaic array here may include a plurality of photovoltaic strings in the above figures, which are not specifically limited herein.
  • the inverter circuit 202 is used to convert the direct current output by the DC/DC circuit 201 into alternating current for output;
  • the sampling circuit for collecting at least one parameter of the input parameter and the output parameter of the DC/DC circuit
  • the controller is configured to control the DC/DC converter circuit when a short circuit occurs at the output end of the DC/DC conversion circuit, the inverter circuit itself or the output end of the inverter circuit according to the at least one parameter.
  • the main power tube of the DC circuit is closed, so that the main power tube and the input end of the DC/DC circuit form a closed loop.
  • the main power tube not only can the main power tube be controlled to close when it is determined that the output end of the DC/DC conversion circuit is short-circuited, but also when the inverter circuit itself is short-circuited or the output end of the inverter circuit is short-circuited, control The main power tube is closed for short circuit protection.
  • At least one item includes voltage and current.
  • the at least one parameter includes: the output voltage of the DC/DC conversion circuit, the output current of the DC/DC conversion circuit, the input voltage of the DC/DC conversion circuit, and the input of the DC/DC conversion circuit current;
  • the controller is configured to control the switching device to close when the at least one parameter satisfies at least one of the following conditions, and the at least one condition includes: the drop speed of the output voltage of the DC/DC conversion circuit exceeds the first Five preset values, the falling speed of the input voltage of the DC/DC conversion circuit exceeds the sixth preset value, the increasing speed of the output current of the DC/DC conversion circuit exceeds the seventh preset value, the DC/DC The increasing speed of the input current of the conversion circuit exceeds the eighth preset value.
  • the fifth preset value, the sixth preset value, the seventh preset value, and the eighth preset value may be set according to actual control requirements and actual application scenarios, which are not specifically limited in the embodiments of the present application.
  • the specific topology of the DC/DC circuit 201 is not specifically limited in this embodiment, for example, it may be a two-level Boost circuit, a three-level Boost circuit, or a BuckBoost circuit.
  • the DC/DC circuit 201 has its own switching device, that is, the main power tube, when a short circuit occurs at the output end of the DC/DC circuit, that is, the input end of the inverter circuit, that is, a short circuit occurs between the DC positive busbar and the DC negative busbar , control the main power tube in the DC/DC circuit to close, and most of the current flows from the main power tube, thereby reducing the current reaching the output end of the DC/DC circuit, that is, reducing the DC bus current, protecting the DC bus from over-current, and then protecting the inverter. device.
  • the main power transistor may be a circuit breaker, a relay, a triode, an IGBT or a MOS and other devices with on and off control.
  • the controller when there are other switches connected in parallel with the main power tube, the controller is also used to control the main power tube in the DC/DC converter to close when the main power tube in the DC/DC converter is closed.
  • the switch is also closed, which can increase the shunt branch, further reduce the current at the output end, and play a protective role.
  • the embodiments of the present application also provide a photovoltaic system, which will be described in detail below with reference to the accompanying drawings.
  • FIG. 7 is a schematic diagram of a photovoltaic system provided by an embodiment of the present application.
  • the photovoltaic system provided in this embodiment includes: a photovoltaic array PV and a photovoltaic device 1000.
  • the photovoltaic device may be the combiner box described in the above embodiment, or the inverter described in the above embodiment.
  • the input terminal of the photovoltaic device 1000 is connected to the photovoltaic array PV.
  • FIG. 7 simply illustrates the connection relationship of the photovoltaic system, and the specific internal connection relationship can be referred to FIG. 3 and FIG. 4 , which will not be repeated here.
  • the input end of the inverter in a general photovoltaic power station is connected to multiple combiner boxes, thereby increasing the power of the inverter, and the output ends of the multiple combiner boxes are connected in parallel, that is, the combiner boxes are at least two ; The output ends of the two combiner boxes are both connected to the input ends of the inverter.
  • the photovoltaic system includes the combiner box described in the above embodiment, that is, when the positive output terminal and the negative output terminal of the combiner box are short-circuited or reversely connected, the switching devices connected in parallel to the positive input terminal and the negative input terminal of the combiner box are closed by controlling , thereby greatly reducing the current at the output end of the combiner box, protecting the power cables at the output end of the combiner box, and protecting the combiner box from being damaged. Therefore, in the photovoltaic system, when a short-circuit fault or a reverse connection fault occurs in the combiner box, protection is performed in time to avoid short-circuit damage to the entire photovoltaic system.
  • the photovoltaic device in the photovoltaic system is an inverter
  • the inverter since the inverter includes a DC/DC conversion circuit, the main power tube in the DC/DC conversion circuit is connected in parallel with the positive input terminal and the negative terminal of the photovoltaic device. Therefore, when a short circuit or reverse connection occurs, controlling the main power tube to close can realize the protection of the output terminal when the short circuit or reverse connection occurs.
  • the embodiments of the present application further provide a protection method for a DC combiner box, which will be described in detail below with reference to the accompanying drawings.
  • FIG. 8 is a flowchart of a protection method for a DC combiner box provided by an embodiment of the present application.
  • the protection method for the DC combiner box provided in this embodiment is applied to the combiner box introduced in the above embodiment; the method includes the following steps:
  • S801 Collect at least one parameter of the input parameter and the output parameter of the combiner box.
  • S802 Determine, according to the at least one parameter, that a short circuit occurs between the positive output cable and the negative output cable of the combiner box, or between the positive output cable and the negative output cable
  • the switching device is controlled to be closed, so that a closed loop is formed between the switching device, the positive input terminal and the negative input terminal.
  • the input parameters of the combiner box can be collected to determine whether there is a short circuit or whether the connection is reversed; the output parameters of the combiner box can also be collected to determine whether a short circuit or reverse connection has occurred.
  • the sampling circuit when the sampling circuit collects the input parameters of the combiner box, it can collect the input voltage of the combiner box or the input current of the combiner box;
  • the sampling circuit collects the output parameters of the combiner box, it can collect the output voltage of the combiner box or the output current of the combiner box.
  • the switching device is controlled to be closed, and the at least one condition includes: the drop speed of the output voltage of the combiner box exceeds a first preset value, the input voltage of the combiner box The falling speed of the voltage exceeds the second preset value, the increasing speed of the output current of the combiner box exceeds the third preset value, and the increasing speed of the input current of the combiner box exceeds the fourth preset value.
  • the decreasing speed and increasing speed of each of the above parameters can be obtained through the parameter change slope.
  • the output voltage of the combiner box is collected, when the corresponding slope exceeds the first preset value when the output voltage drops, it is considered that the output voltage of the combiner box drops rapidly, and it is considered that there is a short circuit between the positive and negative output cables of the combiner box.
  • the judgment methods of other parameters are the same, and will not be repeated here.
  • the method detects at least one of the input parameters and output parameters of the combiner box, and determines by at least one parameter that a short circuit occurs between the positive and negative output cables of the combiner box, or when the positive and negative output cables are reversed, control the The switching device between the positive input terminal and the negative input terminal of the combiner box is closed, because the switching device is connected in parallel with the input terminal of the combiner box. Therefore, when the switching device is closed, the current path is from the positive input terminal of the combiner box through the closed switching device. When the negative input of the combiner box is reached, a closed loop is formed.
  • At least one (item) refers to one or more, and "a plurality” refers to two or more.
  • “And/or” is used to describe the relationship between related objects, indicating that there can be three kinds of relationships, for example, “A and/or B” can mean: only A, only B, and both A and B exist , where A and B can be singular or plural.
  • the character “/” generally indicates that the associated objects are an “or” relationship.
  • At least one item(s) below” or similar expressions thereof refer to any combination of these items, including any combination of single item(s) or plural items(s).
  • At least one (a) of a, b or c can mean: a, b, c, "a and b", “a and c", “b and c", or "a and b and c" ", where a, b, c can be single or multiple.

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Abstract

本申请公开了一种直流汇流箱、逆变器、光伏系统及保护方法，其中汇流箱包括：关器件、采样电路和控制器；开关器件并联在正输入端和负输入端之间；采样电路，用于采集汇流箱的输入参数和输出参数中的至少一项参数；控制器，用于根据至少一项参数，确定输出正线缆和输出负线缆之间发生短路，或输出正线缆和输出负线缆之间反接时，控制开关器件闭合，开关器件、正输入端和负输入端形成闭合回路。汇流箱的输出端或输出端的后级电路发生短路时，大部分短路电流通过闭合的开关器件，形成回流，降低汇流箱输入端产生的电流从汇流箱的输出端输出，避免汇流箱的输出电流太大时造成汇流箱的输出线缆过流烧毁，本方案也可在输出正负线缆接反时保护汇流箱。

Description

一种直流汇流箱、逆变器、光伏系统及保护方法
本申请要求于2020年09月11日提交中国国家知识产权局的申请号为202010953933.8、申请名称为“一种直流汇流箱、逆变器、光伏系统及保护方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光伏发电技术领域，尤其涉及一种直流汇流箱、逆变器、光伏系统及保护方法。
背景技术
目前，随着环境污染越来越严重，全球对于光伏发电越来越重视。
光伏发电时，由于光伏电池发电的电量有限，因此，一般需要多个电池板组串并联在一起输入汇流箱。
参见图1，该图为现有技术提供的一种光伏系统的示意图。
目前，多个电池板组串并联后连接在直流汇流箱的输入端，为了介绍方便，下面将直流汇流箱简称为汇流箱100。汇流箱100的输出端连接逆变器200的输入端。图1中是多个汇流箱100均连接逆变器200的输入端，即多个汇流箱100的输出端并联在逆变器200的输入端。
目前，有的汇流箱具有最大功率追踪(MPPT，Maximum Power Point Tracking)的功能，汇流箱内部设置有DC/DC变换器，一般为升压DC/DC变换器，图1中以升压DC/DC变换器为Boost为例进行介绍。
目前，汇流箱100一般与逆变器200之间距离较远，两者之间通过正负两根线缆连接，实际中正负线缆的绝缘皮容易破损短路或汇流箱的正负线缆连接到逆变器时正负接反了。图1中的虚线表示汇流箱的正负线缆接反时的电流路径。
此时，当各个汇流箱的输出开关(K1-Kn)闭合时，汇流箱的输出电压会被快速拉到零，输出电流为各路输入电池板组串的短路电流之和，所有电流会灌入出现短路的支路或正负线缆接错的汇流箱中，造成线缆过流烧毁或汇流箱损坏。
发明内容
为了解决以上的技术问题，本申请提供一种直流汇流箱、逆变器、光伏系统及保护方法，能够在线缆出现破损短路或者正负线缆接反时，可以及时保护汇流箱和线缆。
本申请提供一种直流汇流箱，汇流箱连接在光伏阵列和逆变器之间，直流汇流箱的正输入端和负输出端之间并联开关器件，该开关器件可以是汇流箱内部已经包括的，也可以额外添加的，本申请实施例不做限定。当控制器确定直流汇流箱的输出端发生短路或者反接时，控制器控制开关器件闭合，开关器件、正输入端和负输入端形成闭合回路。
具体控制器可以根据采样电路采集汇流箱的输入参数和输出参数中的至少一项参数，确定输出正线缆和输出负线缆之间是否发生短路，或，输出正线缆和输出负线缆之间是否反接。
开关器件闭合时，正输入端和负输入端通过闭合的开关器件接通，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。因此，当 汇流箱的输出端或输出端的后级电路发生短路时，大部分短路电流通过闭合的开关器件，形成回流，从而大大降低汇流箱输入端产生的电流从汇流箱的输出端输出，即降低汇流箱的输出电流，从而可以避免汇流箱的输出电流太大时造成汇流箱的输出正线缆和输出负线缆过流烧毁，即保护功率线缆不被过流时烧毁。另外本技术方案也可以在输出正线缆和输出负线缆接反时保护汇流箱。
优选地，采样电路可以采集汇流箱的输出参数，也可以采集汇流箱的输入参数，输出参数可以包括输出电流和输出电压，输入参数可以包括输入电压和输入电流，即采样电路可以采集汇流箱的以下至少一项参数：汇流箱的输出电压、汇流箱的输出电流、汇流箱的输入电压和所述汇流箱的输入电流；控制器，用于在输出电压或输入电压快递下降，或，输入电流或输出电流快速上升时，确定汇流箱的输出端发生短路或反接。即至少一项参数满足以下至少一个条件时，控制器控制开关器件闭合；至少一个条件包括：汇流箱的输出电压的下降速度超过第一预设值、汇流箱的输入电压的下降速度超过第二预设值、汇流箱的输出电流的增加速度超过第三预设值、汇流箱的输入电流的增加速度超过第四预设值。
优选地，当汇流箱内部包括DC/DC变换器时，开关器件由DC/DC变换器中的主功率管来实现，即控制开关器件闭合通过控制主功率管闭合即可。DC/DC变换器将光伏阵列输出的直流电进行变换后输出给所述逆变器；开关器件至少包括DC/DC变换器中的主功率管；控制器控制DC/DC变换器中的主功率管闭合，使主功率管、正输入端和负输入端形成闭合回路。
优选地，当汇流箱的输出端发生短路或反接需要闭合主功率管时，为了保护主功率管在较低电压下动作，保护主功率管不被高压损坏，可以在光伏阵列的电压低于预设电压值时，才控制主功率管动作，即控制器当至少一项参数满足所述至少一个条件，且DC/DC变换器的输入电压小于预设电压值时，控制DC/DC变换器中的主功率管闭合。
优选地，DC/DC变换器至少包括以下任意一种：两电平Boost电路、三电平Boost电路、BuckBoost电路。
优选地，当DC/DC变换器包括三电平Boost电路时，开关器件至少包括三电平Boost电路中两个串联的主功率管，两个串联的主功率管连接在正输入端和负输入端之间；控制器当至少一项参数满足所述至少一个条件，且DC/DC变换器的输入电压小于预设电压值时，控制所述两个串联的主功率管均闭合。
优选地，当汇流箱中即包括DC/DC变换器，其正负输入端之间又包括并联的其他开关时，控制器控制DC/DC变换器中的主功率管闭合时，控制与DC/DC变换器中的主功率管并联的开关也闭合，这样可以增加分流支路，进而更大限度地分流输出端的电流，降低流到汇流箱输出端的电流。
优选地，为了避免汇流箱的输出端出现短路或者反接时，影响后级的逆变器，因此当开关器件闭合后，将汇流箱输出端的输出开关闭合；由于此时汇流箱输出端的电流已经被分流，得以降低，因此，此时断开输出开关容易断开，不会因为电流太大出现黏连无法断开。输出开关串联在汇流箱的正输出端和/或串联在汇流箱的负输出端。
优选地，汇流箱包括至少两个DC/DC变换器，即包括多个DC/DC变换器；至少两个 DC/DC变换器的输出端均并联在一起；至少两个DC/DC变换器的输入端分别连接不同的光伏组串，所有光伏组串形成光伏阵列。
本申请实施例还提供一种逆变器，包括：DC/DC变换电路、逆变电路、采样电路和控制器；DC/DC变换电路的输入端用于连接光伏阵列；DC/DC变换电路将光伏阵列的直流电转换后输出给所述逆变电路；逆变电路将所述DC/DC变换电路输出的直流电转换为交流电进行输出；采样电路用于采集所述DC/DC变换电路的输入参数和输出参数中的至少一项参数。控制器根据至少一项参数确定DC/DC变换电路的输出端、逆变电路自身或逆变电路的输出端出现短路时，控制DC/DC变换电路的主功率管闭合，以使主功率管与DC/DC变换电路的输入端形成闭合回路。
优选地，至少一项参数包括：所述DC/DC变换电路的输出电压、所述DC/DC变换电路的输出电流、所述DC/DC变换电路的输入电压和所述DC/DC变换电路的输入电流；控制器，用于在所述至少一项参数满足以下至少一个条件时，控制所述开关器件闭合，所述至少一个条件包括：所述DC/DC变换电路的输出电压的下降速度超过第五预设值、所述DC/DC变换电路的输入电压的下降速度超过第六预设值、所述DC/DC变换电路的输出电流的增加速度超过第七预设值、所述DC/DC变换电路的输入电流的增加速度超过第八预设值。
本申请实施例还提供一种光伏系统，包括：光伏阵列和光伏设备，光伏设备为以上介绍的汇流箱或以上介绍的逆变器；光伏设备的输入端用于连接光伏阵列。
优选地，当光伏设备为汇流箱时，光伏系统可以包括多个汇流箱，多个汇流箱的输出端可以并联；即汇流箱为至少两个，两个所述汇流箱的输出端均连接所述逆变器的输入端。
该光伏系统，在汇流箱出现短路故障或者接反故障时，及时进行保护，避免短路对于整个光伏系统造成损坏。另外，当该光伏系统中的光伏设备为逆变器时，由于逆变器中包括DC/DC变换电路，而DC/DC变换电路中的主功率管就是并联在光伏设备的正输入端和负输入端之间，因此，在发生短路或反接时，控制主功率管闭合即可实现对于输出端的短路或反接时的保护。
本申请实施例还提供一种直流汇流箱的保护方法，应用于以上介绍的汇流箱；该方法包括：采集所述汇流箱的输入参数和输出参数中的至少一项参数；根据所述至少一项参数，确定所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制所述开关器件闭合，以使所述开关器件、所述正输入端和所述负输入端之间形成闭合回路。
优选地，根据所述至少一项参数，确定所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制所述开关器件闭合，具体包括：在所述至少一项参数满足以下至少一个条件时，控制所述开关器件闭合；所述至少一个条件包括：所述汇流箱的输出电压的下降速度超过第一预设值、所述汇流箱的输入电压的下降速度超过第二预设值、所述汇流箱的输出电流的增加速度超过第三预设值、所述汇流箱的输入电流的增加速度超过第四预设值；所述至少一种参数包括：所述汇流箱的输出电压、所述汇流箱的输出电流、所述汇流箱的输入电压和所述汇流箱的输入电流。
优选地，当所述汇流箱包括DC/DC变换器时，所述开关器件至少包括所述DC/DC变换器中的主功率管；所述控制所述开关器件闭合，具体包括：当所述至少一项参数满足所述至少一个条件，且所述DC/DC变换器的输入电压小于预设电压值时，控制所述DC/DC变换器中的主功率管闭合。
优选地，所述汇流箱还包括：输出开关；所述输出开关串联在所述汇流箱的正输出端和/或串联在所述汇流箱的负输出端；在控制所述DC/DC变换器中的主功率管闭合之后，还包括：控制所述汇流箱的输出开关断开。
该方法通过检测汇流箱的输入参数和输出参数中的至少一项参数，通过至少一项参数确定汇流箱的输出正负线缆之间发生短路，或者输出正负线缆之间接反时，控制汇流箱的正输入端和负输入端之间的开关器件闭合，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。这样当发生短路时，大部分短路电流通过闭合的开关器件，形成回流，从而大大降低从汇流箱输出的电流，因此，可以避免汇流箱的输出电流太大时造成功率线缆过流烧毁，或者输出正负线缆接反时，损坏汇流箱。
与现有技术相比，本申请实施了提供的技术方案具有以下优点：
该方案通过检测汇流箱的输入参数和输出参数中的至少一项参数，通过至少一项参数确定汇流箱的输出正线缆和输出负线缆之间发生短路，或者输出正线缆和输出负线缆之间接反时，控制器用于控制汇流箱的正输入端和负输入端之间的开关器件闭合，由于开关器件并联在汇流箱的正输入端和负输入端之间，因此，开关器件闭合时，正输入端和负输入端通过闭合的开关器件接通，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。因此，当汇流箱的输出端或输出端的后级电路发生短路时，大部分短路电流通过闭合的开关器件，形成回流，从而大大降低汇流箱输入端产生的电流从汇流箱的输出端输出，即降低汇流箱的输出电流，从而可以避免汇流箱的输出电流太大时造成汇流箱的输出正线缆和输出负线缆过流烧毁，即保护功率线缆不被过流时烧毁。另外本技术方案也可以在输出正线缆和输出负线缆接反时保护汇流箱。
附图说明
图1为现有技术提供的一种光伏系统的示意图；
图2为本申请实施例提供的一种直流汇流箱的示意图；
图3为本申请实施例提供的一种包括两电平Boost电路的汇流箱的示意图；
图4为本申请实施例提供的一种包括三电平Boost电路的汇流箱的示意图；
图5为本申请实施例提供的一种简单汇流箱的示意图；
图6为本申请实施例提供的一种逆变器的示意图；
图7为本申请实施例提供的一种光伏系统的示意图；
图8为本申请实施例提供的一种直流汇流箱的保护方法的流程图。
具体实施方式
为了使本领域技术人员更好地理解本申请实施例提供的技术方案，下面先介绍本申请提供的技术方案的应用场景，应用于光伏发电技术领域，在光伏发电系统中，汇流箱是一种常用的设备，一般汇流箱的输入端连接光伏阵列，为了提供发电能力，汇 流箱需要将多个光伏组串的能量进行汇流，由于光伏阵列输出的是直流电，因此，汇流箱又称为直流汇流箱，当然也可以在逆变器侧存在交流汇流箱，本申请实施例中具体介绍直流汇流箱。直流汇流箱的输出端连接逆变器，逆变器将直流电逆变为交流电反馈给交流电网。一般情况下，汇流箱的输出端包括正输出端和负输出端，汇流箱的正输出端通过输出正线缆连接逆变器的正输入端，汇流箱的负输出端通过输出负线缆连接逆变器的负输入端。
本申请实施例提供的技术方案为，当汇流箱的输出正线缆和输出负线缆之间发生短路，或输出正负线缆之间接反时，控制器控制并联在汇流箱的正输入端和负输入端之间的开关器件闭合，从而使汇流箱的正输入端、负输入端和闭合的开关器件形成闭合回路，即利用开关器件在汇流箱的输出端短路或反接时提供电流路径，从而对汇流箱的输出电流实现分流，降低汇流箱的输出端的电流，避免过大的短路电流对输出正线缆和输出负线缆造成损坏，即保护汇流箱的输出正线缆和输出负线缆，另外，在汇流箱的输出正线缆和输出负线缆反接时保护汇流箱不被损坏。
本申请实施例提供的技术方案适用于普通汇流箱，即汇流箱内部不包括DC/DC变换器，例如不具有升压功能的汇流箱，对于普通汇流箱应用该技术方案时，只要汇流箱的正输入端和负输入端之间并联有开关器件即可，当汇流箱没有开关器件时，可以添加这样的开关器件。另外，本申请实施例提供的技术方案也适用于具有变压功能的汇流箱，例如升压功能、降压功能、升降压功能等，即汇流箱内部可以包括DC/DC变换器，例如汇流箱内部包括升压变换器，由于DC/DC变换器自带开关器件，即将DC/DC变换器的主功率管作为开关器件，在汇流箱的输出正线缆和输出负线缆之间短路，或输出正线缆和输出负线缆之间接反时，控制DC/DC变换器中的主功率管闭合即可对汇流箱起到保护作用。
本申请实施例中的开关器件包括但不限于以下器件：IGBT、MOSFET、三极管、继电器、断路器等具有分断能力的开关器件。
为了使本领域技术人员更好地理解和实施本申请实施例提供的技术方案，下面结合附图介绍其具体实现方式。
汇流箱实施例一
参见图2，该图为本申请实施例提供的一种直流汇流箱的示意图。
本实施例提供的直流汇流箱100的输出端连接逆变器200的输入端，即位于直流侧的汇流箱。
下面为了描述方便，将直流汇流箱简称为汇流箱。
汇流箱100的输入端用于连接光伏阵列PV。
实际中，光伏阵列PV可以包括多个光伏组串，多个光伏组串可以并联在一起。为了提供电能输出能力，每个光伏组串包括多个光伏电池板串联在一起。
汇流箱100的正输出端用于通过输出正线缆连接逆变器200的正输入端，汇流箱100的负输出端用于通过输出负线缆连接所述逆变器200的负输入端。
汇流箱100的正输入端连接光伏阵列PV的第一端，汇流箱100的负输入端连接光伏阵列PV的第二端。
汇流箱包括：采样电路101、控制器102和开关器件(图中未示出)。
开关器件连接在汇流箱的所述正输入端和所述负输入端之间。
每个汇流箱都可以包括控制器102，尤其是具有最大功率追踪(MPPT，Maximum Power Point Tracking)功能的汇流箱。
采样电路101，用于采集所述汇流箱100的输入参数和输出参数中的至少一项参数；
控制器102，用于根据所述至少一项参数，确定所述汇流箱的所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制开关器件闭合，以使汇流箱的正输入端、汇流箱的负输入端和开关器件形成闭合回路，即在短路时，电流从汇流箱的正输入端经过开关器件到达汇流箱的负输入端形成回流。
实际应用中，可以采集汇流箱的输入参数来判断汇流箱的输出端以及输出端的后级电路是否发生短路，或者是否发生接反；也可以通过采集汇流箱的输出参数来判断汇流箱的输出端以及输出端的后级电路是否发生短路，或者是否发生接反。
以上的参数包括电压或电流。
例如，当采样电路采集汇流箱的输入参数时，可以采集汇流箱的输入电压或汇流箱的输入电流；
当采样电路采集汇流箱的输出参数时，可以采集汇流箱的输出电压或汇流箱的输出电流。
因为当汇流箱的输出正线缆和输出负线缆之间短路时，汇流箱的输入电压或输出电压会急速下降，而汇流箱的输入电流和输出电流会急速上升，因此，控制器在采样电路采集的至少一项参数满足以下至少一个条件时，确定汇流箱的输出端发生短路或发生反接，控制器控制开关器件闭合，所述至少一个条件包括：所述汇流箱的输出电压的下降速度超过第一预设值、所述汇流箱的输入电压的下降速度超过第二预设值、所述汇流箱的输出电流的增加速度超过第三预设值、所述汇流箱的输入电流的增加速度超过第四预设值。
具体应用时，以上各个参数的下降速度和增加速度均可以通过参数变化斜率来获得。例如采集汇流箱的输出电压，当输出电压下降时对应的斜率超过第一预设值时，视为汇流箱的输出电压急速下降，则判断汇流箱的输出正负线缆之间出现短路。其他参数的判断方式同理，在此不再赘述。
该方案通过检测汇流箱的输入参数和输出参数中的至少一项参数，通过至少一项参数确定汇流箱的输出正线缆和输出负线缆之间发生短路，或者输出正线缆和输出负线缆之间接反时，控制汇流箱的正输入端和负输入端之间的开关器件闭合，由于开关器件并联在汇流箱的正输入端和负输入端之间，因此，开关器件闭合时，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。因此，当发生短路时，大部分短路电流通过闭合的开关器件，从汇流箱的正输入端到 负输入端形成回流，从而大大降低从汇流箱的输入端到达汇流箱输出端的电流，即降低汇流箱的输出电流，因此，可以避免汇流箱的输出电流太大时造成输出正线缆和输出负线缆过流烧毁，或者输出正线缆和输出负线缆接反时，电流太大而损坏汇流箱。
汇流箱实施例二
下面以汇流箱中包括DC/DC变换器为例进行介绍，DC/DC变换器用于将所述光伏阵列输出的直流电进行变换后输出给逆变器；具体以DC/DC变换器为升压变换器Boost为例进行介绍。
汇流箱中的开关器件至少包括DC/DC变换器中的主功率管；
当汇流箱的输出正线缆和输出负线缆之间发生短路或接反时，控制器，具体控制DC/DC变换器中的主功率管闭合，以使所述主功率管、所述正输入端和所述负输入端形成闭合回路。即控制器通过向DC/DC变换器中的主功率管输出脉冲驱动信号，即可实现对于主功率管的控制，例如输出PWM信号，PWM信号的高电平对应主功率管闭合，PWM信号的低电平对应主功率管断开。
本申请实施例中不具体限定DC/DC变换器的具体拓扑形式，例如至少包括以下任意一种：两电平Boost电路、三电平Boost电路、BuckBoost电路。
下面以汇流箱中的DC/DC变换器为两电平Boost电路为例进行介绍。
汇流箱至少包括两个DC/DC变换器；
所述两个DC/DC变换器的输出端并联；
所述两个DC/DC变换器的输入端连接不同的光伏组串，所有所述光伏组串形成所述光伏阵列。
参见图3，该图为本申请实施例提供的一种包括两电平Boost电路的汇流箱的示意图。
以光伏系统中包括n个汇流箱，即汇流箱100-汇流箱10n。n可以为大于等于1的整数。
每个汇流箱包括m个DC/DC变换器为例进行介绍，m可以为大于等于2的整数。
m个DC/DC变换器的输出端并联在一起，n个汇流箱100的输出端均连接逆变器200的输入端，具体可以在逆变器200内部实现并联，当然也可以在逆变器200的外部实现并联。
为了方便理解，以汇流箱100为例进行介绍。每个汇流箱100均包括控制器102，即每个汇流箱100的控制器102独立完成自身对应的汇流箱的控制。
如图3所示，汇流箱100包括m个Boost电路，其中第一个Boost电路的主功率管为Q1_1，二极管为D1_1；第m个Boost电路的主功率管为Qm_1，二极管为Dm_1。
图3中m个Boost电路的输出端并联在一起，即共直流母线，如图3所示，第一汇流箱100对应的直流母线为BUS1，第n汇流箱10n对应的直流母线为BUSn。第一汇流箱100的输出开关为K1，第n汇流箱10n的输出开关为Kn。
需要说明的是，输出开关可以只串联在正输出端，也可以只串联在负输出端，也 可以如图所示，汇流箱的负输出端和正输出端均串联输出开关。
图3中未示出采样电路，仅示意控制器102和供电单元103，以第一汇流箱100为例，包括控制器102和供电单元103。
供电单元103用于给采样电路和控制器102进行供电。
供电单元103的电源来源可以为直流母线，也可以为电池板组串，也可以为其他独立的供电电源，在此不做具体限定。
从图中可以看出，当汇流箱100的输出正线缆P1和输出负线缆N1反接时，汇流箱100的正输出端通过输出正线缆P1连接逆变器的负输入端，汇流箱100的负输出端通过输出正线缆N1连接逆变器的正输入端。图中的箭头所示的为汇流箱100的输出正线缆P1和输出负线缆N1反接时的电流方向。
正常情况下，当汇流箱100的输出正线缆P1和输出负线缆N1没有反接时，汇流箱100的正输出端通过输出正线缆P1连接逆变器的正输入端，汇流箱100的负输出端通过输出正线缆N1连接逆变器的负输入端。
一般为了安全在逆变器200的内部设置有开关S1，即汇流箱的输出端通过开关S1连接逆变器的输入端，当出现故障时，可以通过断开S1，断开汇流箱与逆变器输入端的连接。
例如，当检测汇流箱100的输出端发生短路或者反接时，控制Boost电路的主功率管Q1闭合，Q1闭合后，Q1相当于与D1并联分流电池板组串送入汇流箱的电流，而D1的导通压降比较大，所以电池板组串的大部分短路电流都从Q1上进行回流，流过D1的电流较小，因此，大部分电流不会从汇流箱的输出端流出，这样可以避免汇流箱输出电流过大造成功率线缆过流烧毁，或汇流箱的输出端正负接反时造成损坏。
还有一种情况是，图3的汇流箱包括多个Boost电路并联，每个Boost电路的输入端对应独立的电池板组串，因此，当其中一个Boost电路输入端出现问题例如输入电压急速下降，或输入电流急速上升，则控制该Boost电路中的主功率管闭合，进而保护对应的汇流箱和线缆。
当检测汇流箱100的输出端发生短路或者反接时，控制Boost电路的主功率管Q1-Qm闭合，Q1-Qm闭合后，Q1-Qm相当于与D1-Dm并联分流电池板组串送入汇流箱的电流，而D1-Dm的导通压降比较大，所以电池板组串的大部分短路电流都从Q1-Qm上进行回流，流过D1-Dm的电流较小，因此，大部分电流不会从汇流箱的输出端流出，这样可以避免汇流箱输出电流过大造成功率线缆过流烧毁，或汇流箱的输出端正负接反时造成损坏。
本实施例中当汇流箱中有一处出现短路时，控制所有与故障连接的汇流箱的所有开关管都闭合，避免其他汇流箱的电流流过短路处导致烧毁。
由于电池板组串的输入正端和输入负端之间连接有输入滤波电容，因此，当电池板组串的电压较高时，控制主功率管导通，输入滤波电容放电，流过主功率管的电流会瞬间变大，有可能造成Q1-Qm损坏，因此，需要检测DC/DC变换器的输入电压，即电池板组串对应的PV电压，即控制器具体用于当DC/DC变换器的输入电压小于预 设电压值时，控制DC/DC变换器中的主功率管闭合，此时闭合不会因为过流而损坏主功率管，具体的预设电压值，可以根据主功率管的类型以及耐压耐流的具体参数来设定。
如果汇流箱中还包括与DC/DC变换器中的主功率管并联的开关器件，则控制器102，还用于控制所述DC/DC变换器中的主功率管闭合时，控制与所述DC/DC变换器中的主功率管并联的开关器件，目的是为了进一步对汇流箱的输入电流进行分流，减小流入汇流箱的输出端的电流，进而可以更好地保护汇流箱与逆变器之间的功率线缆，也可以更好地保护汇流箱。
一般地，在汇流箱100的输出端还包括：输出开关K1；K1在输出正线缆和输出负线缆上均存在串联的开关触点。
如图所示，输出开关K1串联在所述汇流箱100的输出端；
所述控制器102，还用于控制所述开关器件闭合时或闭合后，控制所述输出开关断开。K1的作用主要是用于断开汇流箱与逆变器的连接。
当开关器件闭合后，由于开关器件闭合时把汇流箱100输出电压钳位在较低的电压，此时断开K1，避免了K1分断时承受电压太大而无法分断的风险。
另外，当K1断开以后，可以控制开关器件断开，此时，由于K1断开了，因此开关器件断开，也不会对后级电路造成损坏。例如，当K1断开之后，直流母线没有电了，开关器件会自动断开。
本实施例提供的汇流箱，包括两电平Boost电路，当汇流箱的输出端短路或者反接时，控制两电平Boost电路中的主功率管闭合，从而分流输入端的电流，使其经过主功率管形成闭合回路，降低到达汇流箱输出端的电流，从而保护汇流箱输出端的线缆，保护汇流箱不被损坏。由于汇流箱自带Boost电路，因此，可以通过控制Boost电路中的主功率管来实现电流分流，不必增加新的硬件电路，节省成本，控制简单。
汇流箱实施例三
以上介绍的是汇流箱中包括两电平Boost电路，下面以汇流箱中包括三电平带飞跨电容的Boost电路。
参见图4，该图为本申请实施例提供的一种包括三电平Boost电路的汇流箱的示意图。
当所述DC/DC变换器包括三电平Boost电路时，所述开关器件至少包括所述三电平Boost电路中两个串联的主功率管，所述两个串联的主功率管连接在所述正输入端和所述负输入端之间；
所述控制器，具体用于当所述至少一项参数满足所述至少一个条件，且所述DC/DC变换器的输入电压小于预设电压值时，控制所述两个串联的主功率管均闭合。
三电平Boost电路中包括两个主功率管，例如第一个三电平Boost中的Q1_1_1和Q2_1_1，第m个三电平Boost中的两个主功率管为Q1_m_1和Q2_m_1。两个主功率管串联后并联在三电平Boost电路的输入正端和输入负端。
对于三电平Boost电路，确定所述汇流箱的所述输出正线缆和所述输出负线缆之间发生短路，或所述输出正线缆和所述输出负线缆之间反接时，需要控制三电平Boost电路中的两个串联的主功率管均闭合，以使所述主功率管与所述汇流箱的输入端形成闭合回路，即Q1_1_1和Q2_1_1均闭合，Q1_m_1和Q2_m_1均闭合。
三电平Boost电路除了包括两个主功率管以外，还包括两个二极管，如图所示，D1_1_1和D2_1_1，D1_m_1和D2_m_1。
下面以第一个三电平Boost电路为例进行说明，当Q1_1_1和Q2_1_1均闭合时，电池板组串的大部分电流通过Q1_1_1和Q2_1_1，而由于二极管的导通压降大于主功率管的导通压降，因此通过D1_1_1和D2_1_1到达汇流箱输出端的电流大大降低，因此可以保护汇流箱与逆变器之间的功率线缆，而且可以保护汇流箱不被损坏。
其他部分的控制与以上实施例介绍的汇流箱包括两电平Boost电路的工作原理相同，在此不再赘述。例如，供电单元103可以给采样电路和控制器102进行供电。当控制主功率管闭合后，控制K1断开。
图中箭头方向示意的电流路径为汇流箱的输出正线缆和输出负线缆接反时的路径。
本实施例提供的汇流箱，包括三电平Boost电路，因此，当汇流箱的输出端出现短路或者接反时，控制三电平Boost电路中两个的主功率管均闭合，从而分流汇流箱输入端的电流，降低汇流箱输出端的电流，从而保护汇流箱的输出正线缆和输出负线缆，即保护功率线缆不被过流烧毁，而且在输出正线缆和输出负线缆接反时，保护汇流箱不被损坏。由于汇流箱自带三电平Boost电路，因此，可以通过控制三电平Boost电路中的主功率管来实现短路或反接保护，实现短路电流的分流，不必增加新的硬件电路，易于实现，节省成本，而且控制简单。
汇流箱实施例四
以上介绍的是汇流箱带有升压功能，下面介绍汇流箱中不包括DC/DC变换器，仅是简单的汇流作用，即普通汇流箱，汇流箱的输入正端和输入负端之间并联有开关器件即可，当没有这样的开关器件时，可以增加这样的开关器件。
参见图5，该图为本申请实施例提供的一种简单汇流箱的示意图。
本实施例提供的汇流箱100内部不包括DC/DC变换器，汇流箱100仅是简单的汇流作用，即将各路电池板组串的输入电流汇聚在一起输出给逆变器200。
图中以一个汇流箱为例，以每个汇流箱包括两路为例，两路的输入端各自分别连接对应的光伏组串，两路的输出端并联在一起，实现汇流。
本实施例中不具体限定光伏组串的具体个数，也不限定光伏组串中光伏电池的连接关系和数量，例如可以包括多个光伏电池串并联在一起的光伏组串。
汇流箱100每个支路输入端的开关器件Q1和Q2可以是新增的，也可以利用已有的开关器件，当汇流箱100的输出短路或者反接时，控制Q1和Q2闭合，使电流流过Q1和Q2，从而降低到达汇流箱100输出端的电流，保护汇流箱100输出端的线缆以及保护汇流箱不被损坏。同理当Q1和Q2闭合后，控制K断开，由于Q1和Q2短路， 箝位汇流箱的输出电压，即汇流箱的输出电压较低，K容易被断开。如果汇流箱输出电压较高，K存在无法被断开的风险。
图5所示的是汇流箱100的正输出端和负输出端反接的示意图。
本实施例提供的汇流箱，内部可以没有DC/DC变换器，当汇流箱的输出端出现短路或者接反时，可以控制并联在汇流箱的正输入端和负输入端的开关器件闭合，正输入端和负输入端通过闭合的开关器件接通，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。因此，当汇流箱的输出端或输出端的后级电路发生短路时，大部分短路电流通过闭合的开关器件，形成回流，从而大大降低汇流箱输入端产生的电流从汇流箱的输出端输出，即降低汇流箱的输出电流，从而可以避免汇流箱的输出电流太大时造成汇流箱的输出正线缆和输出负线缆过流烧毁，即保护功率线缆不被过流时烧毁。另外本技术方案也可以在输出正线缆和输出负线缆接反时保护汇流箱。
逆变器实施例
以上实施例介绍的是汇流箱和逆变器分离设置，当汇流箱包括DC/DC变换器时，DC/DC变换器设置在汇流箱的内部，逆变器在汇流箱的外部。
本申请实施例还提供一种逆变器，逆变器的内部包括DC/DC变换电路，即逆变器内部包括DC/DC电路也包括逆变电路，逆变器既具有升压功能，又具有逆变功能。
参见图6，该图为本申请实施例提供的一种逆变器的示意图。
本实施例提供一种逆变器200，包括：DC/DC电路201、逆变电路202、采样电路和控制器(图中均未示出)；
所述DC/DC电路201的输入端用于连接光伏阵列PV，用于将所述光伏阵列PV的直流电转换后进行输出。
此处的光伏阵列可以包括以上图中的多个光伏组串，在此不做具体限定。
所述逆变电路202，用于将所述DC/DC电路201输出的直流电转换为交流电进行输出；
所述采样电路，用于采集所述DC/DC电路的输入参数和输出参数中的至少一项参数；
所述控制器，用于根据所述至少一项参数确定所述DC/DC变换电路的输出端、所述逆变电路自身或所述逆变电路的输出端出现短路时，控制所述DC/DC电路的主功率管闭合，以使所述主功率管与所述DC/DC电路的输入端形成闭合回路。
本实施例中，不仅可以在确定所述DC/DC变换电路的输出端出现短路时，控制主功率管闭合，也可以在逆变电路自身出现短路或逆变电路的输出端出现短路时，控制主功率管闭合来实现短路保护。
其中，至少一项包括电压和电流。
所述至少一项参数包括：所述DC/DC变换电路的输出电压、所述DC/DC变换电路的输出电流、所述DC/DC变换电路的输入电压和所述DC/DC变换电路的输入电流；
所述控制器，用于在所述至少一项参数满足以下至少一个条件时，控制所述开关 器件闭合，所述至少一个条件包括：所述DC/DC变换电路的输出电压的下降速度超过第五预设值、所述DC/DC变换电路的输入电压的下降速度超过第六预设值、所述DC/DC变换电路的输出电流的增加速度超过第七预设值、所述DC/DC变换电路的输入电流的增加速度超过第八预设值。
第五预设值、第六预设值、第七预设值和第八预设值可以根据实际的控制需求和实际应用场景来设置，本申请实施例中不做具体限定。
本实施例中不具体限定DC/DC电路201的具体拓扑形式，例如可以为两电平Boost电路，也可以为三电平Boost电路，还可以为BuckBoost电路。
由于DC/DC电路201中自带开关器件，即主功率管，因此，当DC/DC电路的输出端即逆变电路的输入端出现短路时，即直流正母线和直流负母线之间出现短路，控制DC/DC电路中的主功率管闭合，大部分电流从主功率管流过，从而降低到达DC/DC电路输出端的电流，即降低直流母线电流，保护直流母线不过流，进而保护逆变器。
本申请以上实施例均不限定主功率管的具体类型，例如可以为断路器、继电器、三极管、IGBT或者MOS等具有开通和关断控制的器件。
以上实施例中，当存在与主功率管并联的其他开关时，控制器还用于控制DC/DC变换器中的主功率管闭合时，控制与DC/DC变换器中的主功率管并联的开关也闭合，这样可以增加分流支路，进一步降低输出端的电流，起到保护作用。
光伏系统实施例
基于以上实施例提供的一种汇流箱和逆变器，本申请实施例还提供一种光伏系统，下面结合附图进行详细介绍。
参见图7，该图为本申请实施例提供的一种光伏系统的示意图。
本实施例提供的光伏系统，包括：光伏阵列PV和光伏设备1000光伏设备可以为以上实施例介绍的汇流箱，也可以为以上实施例介绍的逆变器。
光伏设备1000的输入端连接光伏阵列PV。
图7仅是简单示意光伏系统的连接关系，具体的内部连接关系可以参见图3和图4，在此不再赘述。
如图3和图4所示，一般光伏电站中的逆变器的输入端连接多个汇流箱，从而增加逆变器的功率，多个汇流箱的输出端并联，即汇流箱为至少两个；两个所述汇流箱的输出端均连接所述逆变器的输入端。
由于该光伏系统中包括以上实施例介绍的汇流箱，即汇流箱的正输出端和负输出端之间短路或者接反时，通过控制并联在汇流箱的正输入端和负输入端开关器件闭合，从而大大降低汇流箱输出端的电流，保护汇流箱输出端的功率线缆，保护汇流箱不被损坏。因此，该光伏系统，在汇流箱出现短路故障或者接反故障时，及时进行保护，避免短路对于整个光伏系统造成损坏。另外，当该光伏系统中的光伏设备为逆变器时，由于逆变器中包括DC/DC变换电路，而DC/DC变换电路中的主功率管就是并联在光伏设备的正输入端和负输入端之间，因此，在发生短路或反接时，控制主功率管闭合 即可实现对于输出端的短路或反接时的保护。
方法实施例
基于以上实施例提供的一种汇流箱、逆变器和光伏系统，本申请实施例还提供一种直流汇流箱的保护方法，下面结合附图进行详细介绍。
参见图8，该图为本申请实施例提供的一种直流汇流箱的保护方法的流程图。
本实施例提供的直流汇流箱的保护方法，应用于以上实施例介绍的汇流箱；该方法包括以下步骤：
S801：采集所述汇流箱的输入参数和输出参数中的至少一项参数。
S802：根据所述至少一项参数，确定所述汇流箱的所述输出正线缆和所述输出负线缆之间发生短路，或所述输出正线缆和所述输出负线缆之间反接时，控制开关器件闭合，以使开关器件、正输入端和所述负输入端之间形成闭合回路。
实际应用中，可以采集汇流箱的输入参数来判断是否发生短路，或者是否发生接反；也可以通过采集汇流箱的输出参数来判断是否发生短路，或者是否发生接反。
例如，当采样电路采集汇流箱的输入参数时，可以采集汇流箱的输入电压或汇流箱的输入电流；
当采样电路采集汇流箱的输出参数时，可以采集汇流箱的输出电压或汇流箱的输出电流。
因为当汇流箱的输出正线缆和输出负线缆之间短路时，汇流箱的输入电流或输出电压会急速下降，而汇流箱的输入电流和输出电流会急速上升，因此控制器在采样电路采集的至少一项参数满足以下至少一个条件时，控制所述开关器件闭合，所述至少一个条件包括：所述汇流箱的输出电压的下降速度超过第一预设值、所述汇流箱的输入电压的下降速度超过第二预设值、所述汇流箱的输出电流的增加速度超过第三预设值、所述汇流箱的输入电流的增加速度超过第四预设值。
具体应用时，以上各个参数的下降速度和增加速度均可以通过参数变化斜率来获得。例如采集汇流箱的输出电压，当输出电压下降时对应的斜率超过第一预设值时，认为汇流箱的输出电压急速下降，则认为汇流箱的输出正负线缆之间出现短路。其他参数的判断方式同理，在此不再赘述。
该方法通过检测汇流箱的输入参数和输出参数中的至少一项参数，通过至少一项参数确定汇流箱的输出正负线缆之间发生短路，或者输出正负线缆之间接反时，控制汇流箱的正输入端和负输入端之间的开关器件闭合，因为开关器件并联在汇流箱的输入端，因此，开关器件闭合时，电流路径为从汇流箱的正输入端通过闭合的开关器件到达汇流箱的负输入端，即形成了闭合回路。这样当发生短路时，大部分短路电流通过闭合的开关器件，形成回流，从而大大降低从汇流箱输出的电流，因此，可以避免汇流箱的输出电流太大时造成功率线缆过流烧毁，或者输出正负线缆接反时，损坏汇流箱。
应当理解，在本申请中，“至少一个(项)”是指一个或者多个，“多个”是指两个或 两个以上。“和/或”，用于描述关联对象的关联关系，表示可以存在三种关系，例如，“A和/或B”可以表示：只存在A，只存在B以及同时存在A和B三种情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b或c中的至少一项(个)，可以表示：a，b，c，“a和b”，“a和c”，“b和c”，或“a和b和c”，其中a，b，c可以是单个，也可以是多个。
以上所述，仅是本申请的较佳实施例而已，并非对本申请作任何形式上的限制。虽然本申请已以较佳实施例揭露如上，然而并非用以限定本申请。任何熟悉本领域的技术人员，在不脱离本申请技术方案范围情况下，都可利用上述揭示的方法和技术内容对本申请技术方案做出许多可能的变动和修饰，或修改为等同变化的等效实施例。因此，凡是未脱离本申请技术方案的内容，依据本申请的技术实质对以上实施例所做的任何简单修改、等同变化及修饰，均仍属于本申请技术方案保护的范围内。

Claims (17)

  1. 一种直流汇流箱，其特征在于，所述汇流箱的正输入端用于连接光伏阵列的第一端，所述汇流箱的负输入端用于连接所述光伏阵列的第二端；所述汇流箱的正输出端用于通过输出正线缆连接逆变器的正输入端，所述汇流箱的负输出端用于通过输出负线缆连接所述逆变器的负输入端；
    所述汇流箱包括：开关器件、采样电路和控制器；
    所述开关器件并联在所述正输入端和所述负输入端之间；
    所述采样电路，用于采集所述汇流箱的输入参数和输出参数中的至少一项参数；
    所述控制器，用于根据所述至少一项参数，确定所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制所述开关器件闭合，以使所述开关器件、所述正输入端和所述负输入端形成闭合回路。
  2. 根据权利要求1所述的汇流箱，其特征在于，所述采样电路，具体用于采集以下至少一项：所述汇流箱的输出电压、所述汇流箱的输出电流、所述汇流箱的输入电压和所述汇流箱的输入电流；
    所述控制器，用于在所述至少一项参数满足以下至少一个条件时，控制所述开关器件闭合；
    所述至少一个条件包括：所述汇流箱的输出电压的下降速度超过第一预设值、所述汇流箱的输入电压的下降速度超过第二预设值、所述汇流箱的输出电流的增加速度超过第三预设值、所述汇流箱的输入电流的增加速度超过第四预设值。
  3. 根据权利要求1所述的汇流箱，其特征在于，所述汇流箱还包括：DC/DC变换器；
    所述DC/DC变换器，用于将所述光伏阵列输出的直流电进行变换后输出给所述逆变器；
    所述开关器件至少包括所述DC/DC变换器中的主功率管；
    所述控制器，具体用于控制所述DC/DC变换器中的主功率管闭合，以使所述主功率管、所述正输入端和所述负输入端形成闭合回路。
  4. 根据权利要求3所述的汇流箱，其特征在于，所述控制器，具体用于当所述至少一项参数满足所述至少一个条件，且所述DC/DC变换器的输入电压小于预设电压值时，控制所述DC/DC变换器中的主功率管闭合。
  5. 根据权利要求4所述的汇流箱，其特征在于，所述DC/DC变换器至少包括以下任意一种：两电平Boost电路、三电平Boost电路、BuckBoost电路。
  6. 根据权利要求5所述的汇流箱，其特征在于，当所述DC/DC变换器包括三电平Boost电路时，所述开关器件至少包括所述三电平Boost电路中两个串联的主功率管，所述两个串联的主功率管连接在所述正输入端和所述负输入端之间；
    所述控制器，具体用于当所述至少一项参数满足所述至少一个条件，且所述DC/DC变换器的输入电压小于预设电压值时，控制所述两个串联的主功率管均闭合。
  7. 根据权利要求3-5任一项所述的汇流箱，其特征在于，所述控制器，还用于控制 所述DC/DC变换器中的主功率管闭合时，控制与所述DC/DC变换器中的主功率管并联的开关闭合。
  8. 根据权利要求1所述的汇流箱，其特征在于，所述汇流箱还包括：输出开关；
    所述输出开关串联在所述汇流箱的正输出端和/或串联在所述汇流箱的负输出端；
    所述控制器，还用于控制所述开关器件闭合后，控制所述输出开关断开。
  9. 根据权利3所述的汇流箱，其特征在于，所述汇流箱包括至少两个DC/DC变换器；
    所述至少两个DC/DC变换器的输出端均并联在一起；
    所述至少两个DC/DC变换器的输入端分别连接不同的光伏组串，所有所述光伏组串形成所述光伏阵列。
  10. 一种逆变器，其特征在于，包括：DC/DC变换电路、逆变电路、采样电路和控制器；
    所述DC/DC变换电路的输入端用于连接光伏阵列；
    所述DC/DC变换电路，用于将所述光伏阵列的直流电转换后输出给所述逆变电路；
    所述逆变电路，用于将所述DC/DC变换电路输出的直流电转换为交流电进行输出；
    所述采样电路，用于采集所述DC/DC变换电路的输入参数和输出参数中的至少一项参数
    所述控制器，用于根据所述至少一项参数确定所述DC/DC变换电路的输出端、所述逆变电路自身或所述逆变电路的输出端出现短路时，控制所述DC/DC变换电路的主功率管闭合，以使所述主功率管与所述DC/DC变换电路的输入端形成闭合回路。
  11. 根据权利要求10所述的逆变器，其特征在于，所述至少一项参数包括：所述DC/DC变换电路的输出电压、所述DC/DC变换电路的输出电流、所述DC/DC变换电路的输入电压和所述DC/DC变换电路的输入电流；
    所述控制器，用于在所述至少一项参数满足以下至少一个条件时，控制所述开关器件闭合，所述至少一个条件包括：所述DC/DC变换电路的输出电压的下降速度超过第五预设值、所述DC/DC变换电路的输入电压的下降速度超过第六预设值、所述DC/DC变换电路的输出电流的增加速度超过第七预设值、所述DC/DC变换电路的输入电流的增加速度超过第八预设值。
  12. 一种光伏系统，其特征在于，包括：光伏阵列和光伏设备，所述光伏设备为权利要求1-9任一项所述的汇流箱或所述权利要求10-11任一项的逆变器；
    所述光伏设备的输入端用于连接所述光伏阵列。
  13. 根据权利要求12所述的光伏系统，其特征在于，当所述光伏设备为汇流箱时，所述汇流箱为至少两个；
    两个所述汇流箱的输出端均连接所述逆变器的输入端。
  14. 一种直流汇流箱的保护方法，其特征在于，应用于权利要求1-9任一项所述的汇流箱；该方法包括：
    采集所述汇流箱的输入参数和输出参数中的至少一项参数；
    根据所述至少一项参数，确定所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制所述开关器件闭合，以使所述开关器件、所述正输入端和所述负输入端之间形成闭合回路。
  15. 根据权利要求14所述的方法，其特征在于，根据所述至少一项参数，确定所述输出正线缆和所述输出负线缆之间发生短路，或，所述输出正线缆和所述输出负线缆之间反接时，控制所述开关器件闭合，具体包括：
    在所述至少一项参数满足以下至少一个条件时，控制所述开关器件闭合；
    所述至少一个条件包括：所述汇流箱的输出电压的下降速度超过第一预设值、所述汇流箱的输入电压的下降速度超过第二预设值、所述汇流箱的输出电流的增加速度超过第三预设值、所述汇流箱的输入电流的增加速度超过第四预设值；
    所述至少一种参数包括：所述汇流箱的输出电压、所述汇流箱的输出电流、所述汇流箱的输入电压和所述汇流箱的输入电流。
  16. 根据权利要求14或15所述的方法，其特征在于，当所述汇流箱包括DC/DC变换器时，所述开关器件至少包括所述DC/DC变换器中的主功率管；所述控制所述开关器件闭合，具体包括：
    当所述至少一项参数满足所述至少一个条件，且所述DC/DC变换器的输入电压小于预设电压值时，控制所述DC/DC变换器中的主功率管闭合。
  17. 根据权利要求16所述的方法，其特征在于，所述汇流箱还包括：输出开关；所述输出开关串联在所述汇流箱的正输出端和/或串联在所述汇流箱的负输出端；
    在控制所述DC/DC变换器中的主功率管闭合之后，还包括：
    控制所述汇流箱的输出开关断开。
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