WO2021195929A1 - 光伏组串的参数曲线扫描方法、变换器及光伏发电系统 - Google Patents

光伏组串的参数曲线扫描方法、变换器及光伏发电系统 Download PDF

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Publication number
WO2021195929A1
WO2021195929A1 PCT/CN2020/082317 CN2020082317W WO2021195929A1 WO 2021195929 A1 WO2021195929 A1 WO 2021195929A1 CN 2020082317 W CN2020082317 W CN 2020082317W WO 2021195929 A1 WO2021195929 A1 WO 2021195929A1
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WO
WIPO (PCT)
Prior art keywords
voltage
parameter curve
curve
terminal
photovoltaic string
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PCT/CN2020/082317
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English (en)
French (fr)
Inventor
徐志武
鞠华磊
顾桂磊
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to JP2022544191A priority Critical patent/JP2023511565A/ja
Priority to CN202211063780.5A priority patent/CN115498959A/zh
Priority to ES20922468T priority patent/ES2961249T3/es
Priority to EP20922468.2A priority patent/EP3926823B1/en
Priority to AU2020439859A priority patent/AU2020439859B2/en
Priority to PCT/CN2020/082317 priority patent/WO2021195929A1/zh
Priority to CN202080005064.4A priority patent/CN112703669B/zh
Priority to EP23178499.2A priority patent/EP4258505A3/en
Publication of WO2021195929A1 publication Critical patent/WO2021195929A1/zh
Priority to US17/689,863 priority patent/US11575266B2/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
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • 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
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • This application relates to the field of photovoltaic power generation technology, and in particular to a parameter curve scanning method of photovoltaic strings, a converter, and a photovoltaic power generation system.
  • Photovoltaic power generation system is a power generation system that uses photovoltaic modules (Solar Cell Module) to directly convert solar energy into electrical energy, including photovoltaic strings, batteries, controllers and photovoltaic inverters.
  • the photovoltaic string includes a plurality of photovoltaic modules combined in series or/and parallel.
  • photovoltaic module refers to the smallest indivisible photovoltaic cell assembly device that can provide direct current output alone.
  • the photovoltaic system can scan the PV strings online; at the same time, the IV curve scanning can also help the photovoltaic system understand the current power generation capacity of the photovoltaic strings , Work status and other information.
  • the IV output characteristics of photovoltaic strings are greatly affected by changes in light. If the photovoltaic system has changes in light during the process of scanning the IV curve of the photovoltaic string, the IV curve of the photovoltaic string will not be accurate. Reflects the IV output characteristics of the photovoltaic string.
  • the embodiment of the application discloses a method for scanning a parameter curve of a photovoltaic string, a converter, and a photovoltaic power generation system, which can determine whether it is affected by changes in light according to the obtained parameter curve, so as to determine whether the currently obtained parameter curve is valid. Improved the reliability of parameter curve scanning.
  • an embodiment of the present application discloses a method for scanning a parameter curve of a photovoltaic string, which controls the output voltage of the photovoltaic string to change from the first end voltage of the first voltage range to the first predetermined rule.
  • the second terminal voltage of the first voltage range and acquiring the current or power parameter of the photovoltaic string during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the first parameter curve;
  • the output voltage of the photovoltaic string is controlled to change from the third terminal voltage of the second voltage range to the fourth terminal voltage of the second voltage range according to a second preset rule, and the output voltage of the photovoltaic string changes In the process of obtaining the current or power parameters of the photovoltaic string to realize the scanning of the second parameter curve; there is an intersection between the first voltage range and the second voltage range.
  • the first voltage range refers to the voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the first parameter curve scan.
  • the second voltage range refers to the voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of scanning the second parameter curve.
  • the maximum output voltage of the photovoltaic string may be the open circuit voltage
  • the minimum output voltage value may be 0V.
  • the obtained first parameter curve and the second parameter curve has the same voltage part, and the current corresponding to the same voltage is obtained at different times, so the current obtained parameter curve can be determined by comparing the current corresponding to the same voltage part Whether there is the influence of illumination changes, it can then be judged whether the currently obtained parameter curve is valid, which improves the reliability of parameter curve scanning.
  • this method does not require additional test equipment, which effectively reduces the hardware equipment that needs to be provided and reduces the cost.
  • the first terminal voltage is greater than the second terminal voltage and the third terminal voltage is less than the fourth terminal voltage; or, the first terminal The point voltage is less than the second terminal voltage and the third terminal voltage is greater than the fourth terminal voltage.
  • the first terminal voltage is equal to the fourth terminal voltage, and/or the second terminal voltage is equal to the first terminal voltage.
  • the waveform of the first voltage range with respect to time is relative to the waveform of the second voltage range with respect to The time waveform is symmetrical.
  • the first preset law is a voltage drop law with a fixed voltage difference
  • the second preset law is a voltage drop with a fixed voltage difference. Rising law; or, the first preset law is a voltage rising law with a fixed differential pressure, and the second preset law is a voltage falling law with a fixed differential pressure.
  • the scanning method further includes: judging whether the currently scanned parameter curve is affected by the change in illumination according to the first parameter curve and the second parameter curve.
  • the judging whether the currently scanned parameter curve is affected by a change in illumination according to the first parameter curve and the second parameter curve includes: The first parameter curve is compared with the second parameter curve to determine whether the light intensity corresponding to the first parameter curve and the light intensity corresponding to the second parameter curve have changed.
  • the absolute value of the difference between the corresponding parameter values of the first parameter curve and the second parameter curve at the same voltage point is less than a preset threshold, it is determined that the current The scanned parameter curve is not affected by changes in illumination.
  • the scanning method further includes: when it is determined that the currently scanned curve is not affected by changes in illumination, the first parameter The curve and the second parameter curve are processed to obtain the final parameter curve.
  • an abnormal signal is issued. Report the current scan failure of the host computer. In this way, the host computer can determine whether to re-send the parameter curve scan command based on the feedback.
  • an embodiment of the present application discloses a converter including an adjustment unit and an acquisition unit.
  • the adjustment unit is used to control the output voltage of the photovoltaic string from the first end voltage of the first voltage range to the second end voltage of the first voltage range according to a first preset rule;
  • the acquisition unit is used for The current parameter and/or power parameter of the photovoltaic string are acquired during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the first parameter curve.
  • the adjusting unit is also used to control the output voltage of the photovoltaic string from the voltage of the third end of the second voltage range to the voltage of the fourth end of the second voltage range according to a second preset rule; the acquisition unit It is also used to obtain the current parameter and/or power parameter of the photovoltaic string during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the second parameter curve; the first voltage range and the first voltage range There is an intersection between the two voltage ranges.
  • the current parameter and/or power parameter of the photovoltaic string are acquired while the voltage parameter is acquired during the change of the output voltage of the photovoltaic string, so that a current-voltage (IV) curve or power-voltage (PV) can be formed. curve.
  • the first voltage range refers to the first voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the first parameter curve scan.
  • the second voltage range refers to the second voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the second parameter curve scan.
  • the maximum output voltage of the photovoltaic string may be the open circuit voltage
  • the minimum output voltage value may be 0V.
  • the first terminal voltage is greater than the second terminal voltage and the third terminal voltage is less than the fourth terminal voltage; or, the first terminal The point voltage is less than the second terminal voltage and the third terminal voltage is greater than the fourth terminal voltage.
  • the first terminal voltage is equal to the fourth terminal voltage, and/or the second terminal voltage is equal to the third terminal voltage.
  • the waveform of the first voltage range with respect to time is symmetrical with the waveform of the second voltage range with respect to time.
  • the first preset law is a voltage drop law with a fixed differential pressure
  • the second preset law is a voltage rise law with a fixed differential pressure
  • the first preset law is a voltage rising law with a fixed differential pressure
  • the second preset law is a voltage falling law with a fixed differential pressure
  • the converter further includes a judging unit; the judging unit is configured to judge the currently scanned parameter curve according to the first parameter curve and the second parameter curve Whether it is affected by changes in light.
  • the judging unit is configured to compare the first parameter curve with the second parameter curve to determine the corresponding to the first parameter curve Whether the light intensity of and the light intensity corresponding to the two-parameter curve have changed.
  • the judging unit is configured to, when the first parameter curve and the second parameter curve are at the same voltage point, the absolute value of the difference between the corresponding parameter values is less than When the threshold is preset, it is determined that the currently scanned parameter curve is not affected by changes in illumination.
  • the converter further includes a processing unit configured to, when it is determined that the currently scanned curve is not affected by changes in illumination, compare the first parameter curve And the second parameter curve are processed to obtain the final parameter curve.
  • the processing unit is further configured to send an abnormal signal when it is determined that the currently scanned curve is affected by a change in illumination.
  • an embodiment of the present application discloses a converter including a DC/DC circuit and a sampling circuit, and the sampling circuit is electrically connected to the DC/DC circuit.
  • the DC/DC circuit is used to control the output voltage of the photovoltaic string from the first end voltage of the first voltage range to the second end voltage of the first voltage range according to a first preset rule; the sampling circuit is used for The current parameter and/or power parameter of the photovoltaic string are acquired during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the first parameter curve.
  • the DC/DC circuit is also used to control the output voltage of the photovoltaic string from the third terminal voltage of the second voltage range to the fourth terminal voltage of the second voltage range according to a second preset rule;
  • the sampling circuit is also used to obtain the current parameter and/or power parameter of the photovoltaic string during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the second parameter curve; There is an intersection between the second voltage ranges.
  • the first voltage range refers to the first voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the first parameter curve scan.
  • the second voltage range refers to the second voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the second parameter curve scan.
  • the maximum output voltage of the photovoltaic string may be the open circuit voltage
  • the minimum output voltage value may be 0V.
  • the first terminal voltage is greater than the second terminal voltage and the third terminal voltage is less than the fourth terminal voltage; or, the first terminal The point voltage is less than the second terminal voltage and the third terminal voltage is greater than the fourth terminal voltage.
  • the first terminal voltage is equal to the fourth terminal voltage, and/or the second terminal voltage is equal to the third terminal voltage.
  • the waveform of the first voltage range with respect to time is symmetrical with the waveform of the second voltage range with respect to time.
  • the first preset law is a voltage drop law with a fixed differential pressure
  • the second preset law is a voltage rise law with a fixed differential pressure
  • the first preset law is a voltage rising law with a fixed differential pressure
  • the second preset law is a voltage falling law with a fixed differential pressure
  • the converter further includes a controller, and the controller is electrically connected to the DC/DC circuit and the sampling circuit, respectively.
  • the controller is used for judging whether the currently scanned parameter curve is affected by the change in illumination according to the first parameter curve and the second parameter curve.
  • the controller is configured to compare the first parameter curve with the second parameter curve to determine the light intensity corresponding to the first parameter curve Whether the light intensity corresponding to the two-parameter curve has changed.
  • the controller is configured to determine that the absolute value of the difference between the corresponding parameter values at the same voltage point of the first parameter curve and the second parameter curve is less than a predetermined value.
  • the threshold it is determined that the currently scanned parameter curve is not affected by the change in illumination.
  • the controller is further configured to process the first parameter curve and the second parameter curve when it is determined that the currently scanned curve is affected by changes in illumination To get the final parameter curve.
  • the controller is further configured to send an abnormal signal when it is determined that the currently scanned curve is affected by a change in illumination.
  • an embodiment of the present application discloses a photovoltaic power generation system, including a power grid and at least one photovoltaic string, the photovoltaic power generation system further includes the second aspect and the converter described in any possible implementation manner of the second aspect; Alternatively, the photovoltaic power generation system further includes the inverter described in the third aspect and any possible implementation manner in the third aspect.
  • the input end of the converter is connected to the at least one photovoltaic string, and the output end of the converter is connected to the power grid.
  • an embodiment of the present application discloses a computer-readable storage medium, the computer-readable storage medium stores a computer program, the computer program includes at least one piece of code, the at least one piece of code can be executed by a computer to control the computer to execute The method described in the first aspect and any possible implementation of the first aspect.
  • Figure 1 is a schematic structural diagram of a photovoltaic power generation system in an embodiment of the application.
  • Figure 2 is an IV curve and PV curve diagram of the photovoltaic string in an embodiment of the application.
  • Fig. 3 is a functional block diagram of a converter in an embodiment of the application.
  • FIG. 4 is a flowchart of an IV curve scanning method of a photovoltaic string in an embodiment of the application.
  • FIG. 5 is a flowchart of an IV curve scanning method of a photovoltaic string in another embodiment of the application.
  • Fig. 6 is an IV scan waveform diagram of a photovoltaic string in an embodiment of the application.
  • Fig. 7 is an IV scan waveform diagram of a photovoltaic string in another embodiment of the application.
  • Fig. 8 is a functional block diagram of the converter in an embodiment of the application.
  • This application provides a photovoltaic power generation system, a converter applied to the photovoltaic power generation system, and a parameter curve scanning method of photovoltaic strings.
  • the parameter curve includes a current voltage (Current Voltage, IV) curve or a power voltage (Power Voltage, PV) curve.
  • the converter can scan the parameter curve of at least one photovoltaic string connected to it to detect whether the photovoltaic string is defective or damaged, and learn the current generating capacity of the photovoltaic power generation system through the scanned parameter curve.
  • FIG. 1 is a schematic structural diagram of a photovoltaic power generation system 1000 according to an embodiment of the application.
  • the photovoltaic power generation system 1000 includes a converter 100, at least one photovoltaic string 300 and a power grid 500.
  • the photovoltaic string 300 includes a plurality of photovoltaic modules 301 combined in series or/and parallel.
  • the photovoltaic module 301 is also called a solar panel, which is the core part of the photovoltaic power generation system. It converts solar energy into electric energy, provides direct current output, and transmits it to the storage battery for storage, or to drive the load to work.
  • a and/or B in this application includes A and B, A or B.
  • the photovoltaic string 300 may also include only one photovoltaic module 301.
  • the converter 100 is connected to at least one photovoltaic string 300 for converting the output power of the photovoltaic module 300 connected to it.
  • the converter 100 is a photovoltaic inverter, and can also be used to convert the direct current output by the at least one photovoltaic string 300 into alternating current and output it to the grid 500.
  • the converter 100 may also be an optimizer, which is not limited here, as long as it can transform the output power of the photovoltaic module 300 connected to it.
  • the power grid 500 is also called a power grid, and includes substations and transmission and distribution lines of various voltages in the power system, namely three units of power transformation, power transmission, and power distribution, which are used to transmit and distribute electrical energy and change voltage.
  • the photovoltaic power generation system 1000 may include a plurality of converters 100, and the AC side of the converter 100 may be connected to a step-up transformer (not shown) and then connected to the power grid 500.
  • the number of converters 100 included in the photovoltaic power generation system 1000 and whether the AC side of the converter 100 is connected to a booster can be determined according to the specific application environment, which is not specifically limited here.
  • the multiple converters 100 may communicate with each other through a communication bus.
  • the communication bus may be an Industry Standard Architecture (ISA) bus, Peripheral Component (PCI) bus, or Extended Industry Standard Architecture (EISA) bus, etc.
  • ISA Industry Standard Architecture
  • PCI Peripheral Component
  • EISA Extended Industry Standard Architecture
  • the bus can be divided into address bus, data bus, control bus, etc., for example, 485 bus.
  • the photovoltaic power generation system 1000 may further include an upper computer (not shown in the figure) for communicating with the converter 100.
  • the upper computer can be an independent communication host or a mobile terminal device.
  • the host computer can communicate with the converter 100 through wireless communication (such as WiFi, Lora, Zigbee, etc.) or PLC communication.
  • FIG. 2 is a typical IV curve and PV curve diagram of the photovoltaic string in an embodiment of the application.
  • the curve L1 is the IV curve of the string
  • the curve L2 is the PV curve of the string.
  • Voc is the open circuit voltage of the photovoltaic string, which is defined as the corresponding string voltage when the string output is no-load.
  • Vmpp is the maximum power point voltage of the string, which is defined as the string voltage corresponding to the maximum output power of the string.
  • the photovoltaic string 300 since the photovoltaic string 300 has the characteristic that the voltage decreases as the current increases, there is an optimal operating point for obtaining the maximum power.
  • the output of the photovoltaic string 300 still changes with the solar radiation intensity and the temperature of the photovoltaic string 300 itself. Since the solar radiation intensity changes, it is obvious that the optimal operating point is also changing. Relative to these changes, the operating point of the photovoltaic string 300 is always at the maximum power point, and the photovoltaic power generation system 1000 always obtains the maximum power output from the photovoltaic string 300. This control is the maximum power tracking control.
  • the biggest feature of the converter 100 used in the photovoltaic power generation system 1000 is that it includes a maximum power point tracking (MPPT) function.
  • MPPT maximum power point tracking
  • FIG. 3 is a functional block diagram of a converter in an embodiment of the application. That is, the converter 100 in FIG. 1 can be realized by the structure in FIG. 3.
  • the converter 100 includes a DC/DC circuit 10, a DC/AC circuit 20, a sampling circuit 30, a controller 40 and a memory 50.
  • the functions of the DC/DC circuit 10, the DC/AC circuit 20, the sampling circuit 30, the controller 40, and the memory 50 can be implemented by integrated circuits. 20.
  • the sampling circuit 30, the controller 40 and the memory 50 are integrated on a PCB (Printed Circuit Board, printed circuit board).
  • PCB Printed Circuit Board, printed circuit board
  • Printed circuit board also known as printed circuit board, is an important electronic component, a support for electronic components, and a carrier for electrical connection of electronic components.
  • the converter 100 includes at least one DC/DC circuit 10.
  • Each DC/DC circuit 10 is connected to a photovoltaic string 300 corresponding to the input terminal of the converter 100 for adjusting the output voltage of the photovoltaic string 300.
  • the converter 100 may only include one DC/DC circuit 10, and the one DC/DC circuit 10 is connected to at least one photovoltaic string 300, that is, the one DC/DC circuit 10 has multiple input terminals. .
  • the DC/DC circuit 10 may also be omitted. In this case, the photovoltaic string 300 needs to be connected to the input end of the DC/AC circuit 20.
  • the DC/DC circuit 10 can work in a power conversion mode for power conversion of the DC power of the photovoltaic string 300 at the input end, and then output the converted DC power to the output end; or Working in the direct mode, the input terminal and the output terminal are directly connected.
  • the DC/DC circuit 10 can be configured according to specific application environments, such as a buck circuit, a boost circuit, or a buck-boost circuit.
  • the input end of the DC/AC circuit 20 is electrically connected to the DC/DC circuit 10, and the output end is electrically connected to the power grid 500, and is used to convert DC power into AC power and input to the power grid 500. It can be understood that in other embodiments, the DC/AC circuit 20 may be omitted, that is, the converter 100 only includes a DC/DC circuit.
  • the sampling circuit 30 is electrically connected to the DC/DC circuit 10 for detecting the output voltage of each photovoltaic string 300 and the current corresponding to the output voltage.
  • the sampling circuit 30 may include a sensor, such as a current sensor.
  • the controller 40 is electrically connected to the DC/DC circuit 10, the DC/AC circuit 20, the sampling circuit 30, and the memory 50, respectively.
  • the controller 40 refers to a component that can coordinate various components according to the functional requirements of the instruction. It is the nerve center and command center of the system. It is usually composed of the instruction register IR (Instruction Register), the program counter PC (Program Counter), and the operation controller OC. (Operation Controller) The three components are extremely important for coordinating the orderly work of the entire system.
  • the controller 40 here may refer to one or more devices, circuits, and/or processing cores for processing data (for example, computer program instructions).
  • the controller 40 may be a processor or a collective name for multiple processing elements.
  • the processor 40 may be a general-purpose central processing unit (Central Processing Unit, CPU), or may be an application-specific integrated circuit (ASIC), or one or more programs used to control the execution of the program of this application.
  • Integrated circuits such as: one or more microprocessors (Digital Signal Processor, DSP), or one or more Field Programmable Gate Array (Field Programmable Gate Array, FPGA).
  • the processor 40 may include one or more CPUs.
  • the memory 50 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, random access memory (RAM), or other types that can store information and instructions
  • the dynamic storage device can also be electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), CD-ROM (Compact Disc Read-Only Memory, CD-ROM), or other optical disk storage, CD-ROM Storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or can be used to carry or store desired program codes in the form of instructions or data structures and can be used by Any other medium accessed by the computer, but not limited to this.
  • the memory 50 may exist independently.
  • the memory 50 may also be integrated with the controller 40. It can be used to store data such as the current, voltage, and power of the photovoltaic string 300.
  • the memory 50 is also used to store application program code for executing the solution of the present application, and the controller 40 controls the execution. That is, the controller 50 is used to execute the application program code stored in the memory 40.
  • the structure illustrated in the embodiment of the present application does not constitute a specific limitation on the converter 100.
  • the converter 100 may include more or less components than shown, or combine certain components, or split certain components, or arrange different components.
  • the illustrated components can be implemented in hardware, software, or a combination of software and hardware.
  • the converter 100 in the embodiment of the present application can also be used to scan the IV curve of the photovoltaic string 300 connected to it to detect whether the photovoltaic string 300 connected to it is defective or damaged.
  • the IV curve can also indicate the current power generation capacity, working conditions and other information of the photovoltaic string 300.
  • the IV output characteristics of photovoltaic strings are greatly affected by changes in light. If the photovoltaic system has changes in light during the process of scanning the IV curve of the photovoltaic string, the IV curve of the photovoltaic string will not be accurate. Reflects the IV output characteristics of the photovoltaic string.
  • an embodiment of the present application also discloses a parameter curve scanning method of a photovoltaic string, which is applied to the aforementioned converter 100.
  • the parameter curve includes one of a current-voltage IV curve or a power-voltage PV curve.
  • the IV curve is taken as an example for description.
  • FIG. 4 is a flowchart of an IV curve scanning method of a photovoltaic string in an embodiment of the application. As shown in Fig. 4, the IV curve scanning method of the photovoltaic string includes the following steps.
  • Step S11 controlling the output voltage of the photovoltaic string to change from the first end voltage of the first voltage range to the second end voltage of the first voltage range according to the first preset rule, and during the process of changing the output voltage of the photovoltaic string Sample the output current of the photovoltaic string to obtain the first IV curve.
  • the first voltage range refers to the voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the first IV curve scan.
  • the maximum output voltage of the photovoltaic string may be the open circuit voltage
  • the minimum output voltage value may be 0V.
  • the first predetermined rule is at least one of a voltage drop rule with a fixed voltage difference or a voltage drop rule with a change in voltage difference.
  • the preset rule that the converter 100 controls the output voltage of the photovoltaic string 300 to change from the open-circuit voltage to the preset minimum value can be gradually reduced by a fixed voltage difference (for example, 25V), or by a constant voltage difference (for example, 25V).
  • the difference changes in the voltage drop law to gradually decrease.
  • the voltage drop rule of the change in voltage difference specifically refers to that the voltage drops faster near the open circuit voltage of the photovoltaic string or near the preset minimum value, and the voltage drops slowly in the middle part.
  • the first preset rule may also be another rule that can realize voltage changes, which is not specifically limited here.
  • Step S12 controlling the output voltage of the photovoltaic string to change from the third terminal voltage of the second voltage range to the fourth terminal voltage of the second voltage range according to the second preset law, and the output voltage of the photovoltaic string is changed during the change of the output voltage of the photovoltaic string.
  • the output current of the photovoltaic string is sampled to obtain the second IV curve; there is an intersection between the first voltage range and the second voltage range.
  • the second voltage range refers to the voltage scan range formed by the maximum output voltage and the minimum output voltage of the photovoltaic string in the process of performing the second IV curve scan.
  • the maximum output voltage of the photovoltaic string can be the open circuit voltage
  • the minimum output voltage can be 0V.
  • the second preset law is similar to the first preset law, and will not be repeated here.
  • step S11 and step 12 can be implemented by the DC/DC circuit 10 and the sampling circuit 30.
  • the DC/DC circuit 10 actively adjusts the input power corresponding to the photovoltaic string 300, and then controls the output voltage of the photovoltaic string 300 to the corresponding terminal voltage.
  • the IV curve scanning method of the photovoltaic string disclosed in the embodiment of the application since the first voltage range and the second voltage range of the IV curve scanning are performed on the photovoltaic string, and there is an intersection between the first voltage range and the second voltage range, In turn, the obtained first IV curve and the second IV curve have the same voltage part, and the current corresponding to the same voltage is obtained at different times, so the current corresponding to the same voltage part is compared It can be determined whether the currently obtained IV curve has the influence of illumination, and then it can be judged whether the currently obtained IV curve is valid, which improves the reliability of scanning. In addition, this method does not require additional test equipment, which effectively reduces the hardware equipment that needs to be provided, and reduces the cost of curve scanning.
  • FIG. 5 is a flowchart of an IV curve scanning method of a photovoltaic string in another embodiment of the application. Compared with FIG. 4, the difference is that the IV curve scanning method in this embodiment further includes the following steps.
  • step S13 it is judged whether an IV curve scan command is received. If yes, proceed to step S11; if not, proceed to step S13.
  • step S13 needs to be performed before step S11 is performed.
  • Step S14 judging whether the currently scanned IV curve is affected by the change in illumination according to the first IV curve and the second IV curve. If not, go to step S15; if yes, go to step S16.
  • the controller 40 compares the first parameter curve with the second parameter curve to determine whether the light intensity corresponding to the first IV curve and the light intensity corresponding to the second IV curve have changed . Specifically, if the absolute value of the difference between the current values corresponding to the first IV curve and the second IV curve at the same voltage point is less than the preset threshold, the controller 40 determines that the current IV curve is not affected by the light, that is, the current IV curve is not affected by the light. The obtained IV curve is valid.
  • the current of the photovoltaic string 300 under the same output voltage should be the same.
  • the two sampling currents under the same voltage may have some errors, or although the illumination will change slightly during the two current sampling processes, it can be regarded as no illumination. Therefore, as long as the absolute value of the difference between the two sampling currents under the same voltage is within the allowable range, it can be determined that the currently acquired IV curve is not affected by the change in illumination.
  • the preset threshold can be determined according to actual application conditions, and is not limited here.
  • Step S15 processing the first IV curve and the second IV curve to obtain a final IV curve.
  • the accuracy of the curve can be comprehensively processed on the first IV curve and the second IV curve, for example, the current corresponding to the same voltage point is averaged, and then the final IV curve is obtained and sent to the host computer.
  • step S16 an abnormal signal is issued.
  • the host computer can determine whether to re-send the parameter curve scan command based on the feedback.
  • the first terminal voltage is greater than the second terminal voltage, that is, the first terminal voltage is the upper limit voltage of the first voltage range, and the second terminal voltage is within the first voltage range. Lower limit voltage.
  • the third terminal voltage is less than the fourth terminal voltage, that is, the third terminal voltage is the lower limit voltage of the second voltage range, and the fourth terminal voltage is the upper limit voltage of the second voltage range.
  • the end point of the first IV curve scan and the start point of the second IV curve scan are relatively close, so that the speed of the IV curve scan can be increased.
  • the upper limit voltage of the first voltage range is set to be less than or equal to the string open circuit voltage Voc and greater than the string maximum power point voltage Vmpp; in practical applications, the first voltage range The upper limit voltage can be close to and slightly smaller than the string open circuit voltage.
  • the lower limit voltage of the first voltage range is set to be greater than or equal to zero and less than the maximum power point voltage Vmpp of the string. In practical applications, the lower limit voltage of the first voltage range may be close to and slightly greater than zero.
  • the upper limit voltage of the second voltage range is set to be less than or equal to the string open circuit voltage Voc and greater than the string maximum power point voltage Vmpp; in practical applications, the upper limit voltage of the second voltage range can be close to and slightly smaller than the string open circuit Voltage.
  • the lower limit voltage of the second voltage range is set to be greater than or equal to zero and less than the maximum power point voltage Vmpp of the string; in practical applications, the lower limit voltage of the second voltage range can be close to and slightly greater than zero.
  • the upper limit voltage of the second voltage range may be equal to the upper limit voltage of the first voltage range or not equal to the upper limit voltage of the first voltage range; the lower limit voltage of the second voltage range may be equal to the lower limit voltage of the first voltage range, or Not equal to the lower limit voltage of the first voltage range.
  • the upper limit voltage of the first voltage range is equal to the upper limit voltage of the second voltage range
  • the lower limit voltage of the first voltage range is equal to the second voltage range.
  • the lower limit voltages of the ranges are equal. That is, the first voltage range and the second voltage range completely overlap.
  • the first preset rule and the second preset rule are both voltages with a fixed voltage difference.
  • the first preset law is a voltage drop law with a fixed differential pressure
  • the second preset law is a voltage rise law with a fixed differential pressure.
  • 32 sampling points may be taken in the first voltage range and the second voltage range respectively.
  • the upper limit voltage of the first voltage range is the open circuit voltage Voc of the photovoltaic string 300, and the lower limit voltage of the first voltage range is 0V.
  • the sampling points of the first voltage range are exactly the same as the sampling points of the second voltage range, which reduces the amount of calculation and improves the speed of comparison.
  • FIG. 6 is an IV scan waveform diagram of the photovoltaic string in an embodiment of the application.
  • the waveform F1 of the first voltage range with respect to time is symmetrical with the waveform F2 of the second voltage range with respect to time.
  • a1 is the upper limit voltage of the first voltage range
  • b1 is the lower limit voltage of the first voltage range
  • c1 is the lower limit voltage of the second voltage range
  • d1 is the upper limit voltage of the second voltage range.
  • the first terminal voltage is less than the second terminal voltage, that is, the first terminal voltage is the lower limit voltage of the first voltage range, and the second terminal voltage is the first voltage range The upper limit voltage.
  • the third terminal voltage is greater than the fourth terminal voltage, that is, the third terminal voltage is the upper limit voltage of the second voltage range, and the fourth terminal voltage is the lower limit voltage of the second voltage range.
  • Other details are the same as those in the previous embodiment. The same or similar, so I won’t repeat them here.
  • the IV scan waveform in the embodiment of the present application is shown in FIG. 7, the waveform F3 of the first voltage range with respect to time is symmetrical with the waveform F4 of the second voltage range with respect to time.
  • a2 is the lower limit voltage of the first voltage range
  • b2 is the upper limit voltage of the first voltage range
  • c2 is the upper limit voltage of the second voltage range
  • d2 is the lower limit voltage of the second voltage range.
  • FIG. 8 is a functional block diagram of the converter in an embodiment of the application.
  • the converter 100 is presented in the form of a functional unit.
  • the "unit" here can refer to a specific application integrated circuit, a controller and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above-mentioned functions.
  • the converter 100 may adopt the form shown in FIG. 8.
  • the converter 100 includes an adjustment unit 101, an acquisition unit 102, a judgment unit 103 and a processing unit 104.
  • the adjusting unit 101 is configured to control the output voltage of the photovoltaic string from the first end voltage of the first voltage range to the second end voltage of the first voltage range according to a first preset rule.
  • the acquiring unit 102 is configured to acquire the current of the photovoltaic string during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the first IV curve.
  • the adjusting unit 101 is further configured to control the output voltage of the photovoltaic string from the third terminal voltage of the second voltage range to the fourth terminal voltage of the second voltage range according to a second preset rule.
  • the acquiring unit 102 is further configured to acquire the current of the photovoltaic string during the change of the output voltage of the photovoltaic string, so as to realize the scanning of the second IV curve.
  • the judging unit 103 is configured to judge whether the currently scanned parameter curve is affected by the change in illumination according to the first IV curve and the second IV curve. Specifically, the judging unit 103 is configured to determine the current scanned value when the absolute value of the difference between the corresponding current values of the first IV curve and the second IV curve at the same voltage point is less than a preset threshold value. The IV curve is not affected by changes in illumination.
  • the processing unit 104 is configured to process the first IV curve and the second IV curve to obtain the final IV curve when it is determined that the currently scanned curve is not affected by the change in illumination.
  • the processing unit 104 is also used to send an abnormal signal when it is determined that the currently scanned curve is affected by the change in illumination.
  • the adjustment unit 101 can be implemented by a DC/DC circuit 101.
  • the acquiring unit 102 may be implemented by the sampling circuit 20, and the judging unit 103 and the processing unit 104 may be implemented by the controller 50.
  • the embodiment of the present application also provides a computer storage medium for storing computer software instructions used for the converter shown in FIG. 8 above, which contains the program designed for executing the above method embodiment.
  • the IV curve of the photovoltaic string can be scanned, and it can be further determined whether it is affected by the change in light.
  • the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may be separately physically included, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk).

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Abstract

本申请涉及光伏发电系统中的变换器及光伏组串的参数曲线扫描方法。参数曲线包括电流电压曲线或者功率电压曲线。扫描方法包括：控制光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至第一电压范围的第二端点电压，以实现第一参数曲线的扫描；控制光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至第二电压范围的第四端点电压，以实现第二参数曲线的扫描；第一电压范围和第二电压范围存在交集。本申请根据第一参数曲线和第二参数曲线即可以判断所扫描的曲线是否存在光照变化的影响，方便快捷且无需额外的硬件测试设备。

Description

光伏组串的参数曲线扫描方法、变换器及光伏发电系统 技术领域
本申请涉及光伏发电技术领域，尤其涉及光伏组串的参数曲线扫描方法、变换器及光伏发电系统。
背景技术
光伏发电系统是利用光伏组件(Solar Cell Module)直接将太阳能转换成电能的发电系统，包括光伏组串、蓄电池、控制器和光伏逆变器。光伏组串包括多个以串联或/和并联的方式组合在一起的光伏组件。其中光伏组件是指能够单独提供直流电输出，最小不可分割的光伏电池组合装置。
目前，为了对光伏组串进行检测以判断其是否存在缺陷或损坏，光伏系统可以在线对光伏组串进行IV曲线扫描；同时，通过IV曲线扫描也能帮助光伏系统了解光伏组串当前的发电能力、工作状况等信息。然而，光伏组串的IV输出特性受光照变化影响较大，如果光伏系统在对光伏组串进行IV曲线扫描的过程中有光照的变化，会使得检测得到的光伏组串的IV曲线将不能准确反映光伏组串的IV输出特性。
发明内容
本申请实施例公开了一种光伏组串的参数曲线扫描方法、变换器及光伏发电系统，能够根据已获得的参数曲线确定是否受到光照变化的影响，从而可以确定当前获得的参数曲线是否有效，提高了参数曲线扫描的可靠性。
第一方面，本申请实施例公开一种光伏组串的参数曲线扫描方法，控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压，并在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流或功率参数，以实现第一参数曲线的扫描；
控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压，并在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流或功率参数，以实现第二参数曲线的扫描；所述第一电压范围和所述第二电压范围存在交集。
其中，所述第一电压范围是指在进行第一参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的电压扫描范围。所述第二电压范围是指在进行第二参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的电压扫描范围。例如，光伏组串的最大输出电压可以是开路电压，最小输出电压值可以是0V。
第一方面的技术方案，由于对光伏组串分别进行第一电压范围和第二电压范围的参数曲线扫描，且第一电压范围和第二电压范围存在交集，进而使得获取的第一参数曲线和第二参数曲线存在电压相同的部分，而该相同的电压所对应的电流由于是在不同时间获得的，因此通过对该相同电压部分所对应的电流进行比对即可确定当前所获得的参数曲线是否存在光照变化影响，进而可以判断当前所获得的参数曲线是否有效，提高了参数曲线扫描的 可靠性。此外，该方法无需外加测试设备，有效减少了需要提供的硬件设备，降低了成本。
根据第一方面，在一种可能的实现方式中，所述第一端点电压大于所述第二端点电压且所述第三端点电压小于所述第四端点电压；或者，所述第一端点电压小于所述第二端点电压且所述第三端点电压大于所述第四端点电压。如此，第一参数曲线扫描的终点和第二参数曲线扫描的起点比较靠近，进而可以提高参数曲线扫描的速度。
根据第一方面，在一种可能的实现方式中，为了提高比对的精度，所述第一端点电压等于所述第四端点电压，和/或，所述第二端点电压等于所述第三端点电压。
根据第一方面，在一种可能的实现方式中，为了进一步提高比对的效率，使得两次的采样点数据完全相同，所述第一电压范围关于时间的波形与所述第二电压范围关于时间的波形对称。
根据第一方面，在一种可能的实现方式中，为了提高比对效率，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律；或者，所述第一预设规律为固定压差的电压上升规律，且所述第二预设规律为固定压差的电压下降规律。
根据第一方面，在一种可能的实现方式中，所述扫描方法还包括：根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响。
根据第一方面，在一种可能的实现方式中，所述根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响，包括：将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一参数曲线所对应的光照强度和所述二参数曲线所对应的光照强度是否发生改变。
根据第一方面，在一种可能的实现方式中，若所述第一参数曲线和第二参数曲线在相同的电压点所述对应的参数值的差值的绝对值小于预设阈值，确定当前所扫描的参数曲线未受到光照变化的影响。
根据第一方面，在一种可能的实现方式中，为了进一步提高所获得曲线的精度，所述扫描方法还包括：当确定当前所扫描的曲线未受到光照变化影响时，对所述第一参数曲线和所述第二参数曲线进行处理，以得到最终的参数曲线。
根据第一方面，在一种可能的实现方式中，当确定当前所扫描的曲线受到光照变化影响时，发出异常信号。以上报上位机当前扫描失败，如此，上位机可以根据反馈确定是否从新发送参数曲线扫描指令。
第二方面，本申请实施例公开一种变换器，包括调节单元和获取单元。调节单元用于控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压；获取单元用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第一参数曲线的扫描。所述调节单元还用于控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压；所述获取单元还用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第二参数曲线的扫描；所述第一电压范围和所述第二电压范围存在交集。
可以理解，在光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数的同时也获取电压参数，从而可以形成电流电压(IV)曲线或者功率电压(PV)曲线。
其中，所述第一电压范围是指在进行第一参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的第一电压扫描范围。所述第二电压范围是指在进行第二参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的第二电压扫描范围。例如，光伏组串的最大输出电压可以是开路电压，最小输出电压值可以是0V。
根据第二方面，在一种可能的实现方式中，所述第一端点电压大于所述第二端点电压且所述第三端点电压小于所述第四端点电压；或者，所述第一端点电压小于所述第二端点电压且所述第三端点电压大于所述第四端点电压。
根据第二方面，在一种可能的实现方式中，所述第一端点电压等于所述第四端点电压，和/或，所述第二端点电压等于所述第三端点电压。
根据第二方面，在一种可能的实现方式中，所述第一电压范围关于时间的波形与所述第二电压范围关于时间的波形对称。
根据第二方面，在一种可能的实现方式中，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律；或者，所述第一预设规律为固定压差的电压上升规律，且所述第二预设规律为固定压差的电压下降规律。
根据第二方面，在一种可能的实现方式中，所述变换器还包括判断单元；所述判断单元用于根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响。
根据第二方面，在一种可能的实现方式中，所述判断单元用于用于将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一参数曲线所对应的光照强度和所述二参数曲线所对应的光照强度是否发生改变。
根据第二方面，在一种可能的实现方式中，所述判断单元用于在所述第一参数曲线和第二参数曲线在相同的电压点所述对应的参数值的差值的绝对值小于预设阈值时，确定当前所扫描的参数曲线未受到光照变化的影响。
根据第二方面，在一种可能的实现方式中，所述变换器还包括处理单元，所述处理单元用于在确定当前所扫描的曲线未受到光照变化影响时，对所述第一参数曲线和所述第二参数曲线进行处理，以得到最终的参数曲线。
根据第二方面，在一种可能的实现方式中，所述处理单元还用于在确定当前所扫描的曲线受到光照变化影响时，发出异常信号。
第三方面，本申请实施例公开一种变换器，包括DC/DC电路和采样电路，采样电路和DC/DC电路电连接。DC/DC电路用于控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压；采样电路用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第一参数曲线的扫描。所述DC/DC电路还用于控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压；所述采样 电路还用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第二参数曲线的扫描；所述第一电压范围和所述第二电压范围存在交集。
其中，所述第一电压范围是指在进行第一参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的第一电压扫描范围。所述第二电压范围是指在进行第二参数曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的第二电压扫描范围。例如，光伏组串的最大输出电压可以是开路电压，最小输出电压值可以是0V。
根据第三方面，在一种可能的实现方式中，所述第一端点电压大于所述第二端点电压且所述第三端点电压小于所述第四端点电压；或者，所述第一端点电压小于所述第二端点电压且所述第三端点电压大于所述第四端点电压。
根据第三方面，在一种可能的实现方式中，所述第一端点电压等于所述第四端点电压，和/或，所述第二端点电压等于所述第三端点电压。
根据第三方面，在一种可能的实现方式中，所述第一电压范围关于时间的波形与所述第二电压范围关于时间的波形对称。
根据第三方面，在一种可能的实现方式中，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律；或者，所述第一预设规律为固定压差的电压上升规律，且所述第二预设规律为固定压差的电压下降规律。
根据第三方面，在一种可能的实现方式中，所述变换器还包括控制器，所述控制器分别和所述DC/DC电路和所述采样电路电连接。所述控制器用于根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响。
根据第三方面，在一种可能的实现方式中，所述控制器用于将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一参数曲线所对应的光照强度和所述二参数曲线所对应的光照强度是否发生改变。
根据第三方面，在一种可能的实现方式中，所述控制器用于在所述第一参数曲线和第二参数曲线在相同的电压点所述对应的参数值的差值的绝对值小于预设阈值时，确定当前所扫描的参数曲线未受到光照变化的影响。
根据第三方面，在一种可能的实现方式中，所述控制器还用于在确定当前所扫描的曲线受到光照变化影响时，对所述第一参数曲线和所述第二参数曲线进行处理，以得到最终的参数曲线。
根据第三方面，在一种可能的实现方式中，所述控制器还用于在确定当前所扫描的曲线受到光照变化影响时，发出异常信号。
第四方面，本申请实施例公开一种光伏发电系统，包括电网和至少一个光伏组串，所述光伏发电系统还包括第二方面以及第二方面中任一可能的实现方式描述的变换器；或者，所述光伏发电系统还包括第三方面以及第三方面中任一可能的实现方式描述的变换器。所述变换器的输入端连接所述至少一个光伏组串，且所述变换器的输出端连接所述电网。
第五方面，本申请实施例公开一种计算机可读存储介质，该计算机可读存储介质存储有计算机程序，该计算机程序包含至少一段代码，该至少一段代码可由计算机执行，以控 制所述计算机执行第一方面以及第一方面中任一可能的实现方式描述的方法。
附图说明
图1为本申一请实施例中的光伏发电系统的结构示意图。
图2为本申请一实施例中的光伏组串的IV曲线和PV曲线图。
图3为本申请一实施例中的变换器的原理框图。
图4为本申请一实施例中的光伏组串的IV曲线扫描方法的流程图。
图5为本申请另一实施例中的光伏组串的IV曲线扫描方法的流程图。
图6为本申请一实施例中的光伏组串的IV扫描波形图。
图7为本申请另一实施例中的光伏组串的IV扫描波形图。
图8为本申请一实施例中的变换器的功能模块图。
具体实施方式
本申请提供一种光伏发电系统、应用于光伏发电系统中的变换器以及光伏组串的参数曲线扫描方法。该参数曲线包括电流电压(Current Voltage，IV)曲线或者功率电压(Power Voltage，PV)曲线。变换器可以对与其连接的至少一个光伏组串进行参数曲线扫描，以检测光伏组串是否存在缺陷或损坏，并通过扫描到的参数曲线了解当前光伏发电系统的发电能力。下面结合附图，对本申请的实施例进行描述。
请参阅图1，图1为本申请一实施例提供的光伏发电系统1000的结构示意图。如图1所示，所述光伏发电系统1000包括变换器100、至少一个光伏组串300及电网500。光伏组串300包括多个以串联或/和并联的方式组合在一起的光伏组件301。光伏组件301也称为太阳能电池板，是光伏发电系统中的核心部分，将太阳能转化为电能，提供直流电输出，并传输至蓄电池中存储起来，或推动负载工作。单体太阳电池不能直接作为电源使用的，需要将若干单体电池串联或/和并联连接和严密封装成组件，是最小不可分割的光伏电池组合装置。其中本申请中的“A和/或B”包括了A和B，A或B。
当然，在一些实施例中，光伏组串300也可以只包括一个光伏组件301。
变换器100与至少一个光伏组串300相连，用于对与其相连的光伏组件300的输出功率进行变换。本申请实施例中，变换器100为光伏逆变器，还可以用于将至少一个光伏组串300输出的直流电转换成交流电后输出至电网500。其他实施例中，所述变换器100还可以是优化器，在此不做限定，只要能对与其相连的光伏组件300的输出功率进行变换即可。
电网500也称为电力网，包括电力系统中各种电压的变电所及输配电线路，即变电、输电、配电三个单元，用于输送与分配电能，改变电压。
可以理解，光伏发电系统1000可以包括多个变换器100，且变换器100的交流侧可以接升压变压器(图未示)再接电网500。具体的，光伏发电系统1000所包括的变换器100的数量，以及变换器100的交流侧是否接升压器，可以依据具体应用环境而定，此处不做具体限定。
需要说明的是，在一种实施例中，当光伏发电系统1000包括多台变换器100时，多台 变换器100之间可以采用通信总线进行通信。通信总线可以是工业标准体系结构(Industry Standard Architecture，ISA)总线、外部设备互连(Peripheral Component，PCI)总线或扩展工业标准体系结构(Extended Industry Standard Architecture，EISA)总线等。该总线可以分为地址总线、数据总线、控制总线等，例如，485总线。
此外，在一具体的实施方式中，光伏发电系统1000还可包括一个上位机(图未示)，用于与变换器100进行通信。其中，上位机可以是独立的通信主机，也可以是移动终端设备。上位机可以通过无线通信(如WiFi、Lora、Zigbee等)或者PLC通信与变换器100进行通信。
请参阅图2，图2为本申请一实施例中的光伏组串的典型IV曲线和PV曲线图。如图2所示，曲线L1为组串的IV曲线，曲线L2为组串的PV曲线。其中Voc为光伏组串的开路电压，定义为组串输出空载时对应的组串电压。Vmpp为组串的最大功率点电压，定义为组串输出功率最大时对应的组串电压。
从图2中可以看出，由于光伏组串300具有电压随电流增大而下降的特性，因此存在能获取最大功率的最佳工作点。此外，光伏组串300的输出还是随太阳辐射强度和光伏组串300的自身温度而变化的，由于太阳辐射强度是变化着的，显然最佳工作点也是在变化的。相对于这些变化，始终让光伏组串300的工作点处于最大功率点，光伏发电系统1000始终从光伏组串300获取最大功率输出，这种控制就是最大功率跟踪控制。光伏发电系统1000用的变换器100的最大特点就是包括了最大功率点跟踪(Maximum Power Point Tracking，MPPT)功能。
请参阅图3，图3为本申请一实施例中的变换器的原理框图。也即，图1中的变换器100可以通过图3中的结构来实现。如图3所示，变换器100包括DC/DC电路10、DC/AC电路20、采样电路30、控制器40和存储器50。其中，DC/DC电路10、DC/AC电路20、采样电路30、控制器40和存储器50的功能可以用集成电路来实现，将直流转直流DC/DC电路10、直流转交流DC/AC电路20、采样电路30、控制器40和存储器50集成在PCB(Printed Circuit Board，印制电路板)上。印制电路板又称印刷线路板，是重要的电子部件，是电子元器件的支撑体，是电子元器件电气连接的载体。
本申请实施例中，变换器100包括至少一个DC/DC电路10。每个DC/DC电路10对应连接一个光伏组串300，作为变换器100的输入端，用于调节光伏组串300的输出电压。在其他实施例中，变换器100可以只包括一个DC/DC电路10，该一个DC/DC电路10与至少一个光伏组串300连接，也即，该一个DC/DC电路10具有多个输入端。此外，在一些实施例中，DC/DC电路10也可以省略，此时需要将光伏组串300与DC/AC电路20的输入端连接。
在一具体的实施例中，DC/DC电路10可以工作于功率变换模式，用于对输入端的光伏组串300的直流电能进行功率变换，再输出变换后的直流电能到输出端；或者，可以工作于直通模式，将输入端和输出端直接连通。在具体的实际应用中，DC/DC电路10可以根据具体应用环境进行电路设置，例如设置buck电路、boost电路或者buck-boost电路等。
DC/AC电路20的输入端与DC/DC电路10电连接，且输出端与电网500电连接，用于将直流电能转换为交流电能输入给电网500。可以理解，在其他实施例中，该DC/AC电 路20可以省略，也即，该变换器100只包括DC/DC电路即可。
采样电路30与DC/DC电路10电连接，用于检测每个光伏组串300的输出电压和输出电压所对应的电流。在具体的实际应用中，采样电路30可以包括传感器，例如电流传感器。
控制器40分别与DC/DC电路10、DC/AC电路20、采样电路30和存储器50电连接。控制器40是指能够将各个部件按照指令的功能要求协调工作的部件，是系统的神经中枢和指挥中心，通常由指令寄存器IR(Instruction Register)、程序计数器PC(Program Counter)和操作控制器OC(Operation Controller)三个部件组成，对协调整个系统有序工作极为重要。这里的控制器40可以指一个或多个设备、电路、和/或用于处理数据(例如计算机程序指令)的处理核。
其他实施例中，控制器40可以是一个处理器，也可以是多个处理元件的统称。例如，处理器40可以是一个通用中央处理器(Central Processing Unit，CPU)，也可以是特定应用集成电(application-specific Integrated Circuit，ASIC)，或一个或多个用于控制本申请方案程序执行的集成电路，例如：一个或多个微处理器(Digital Signal Processor，DSP)，或，一个或者多个现场可编程门阵列(Field Programmable Gate Array，FPGA)。在具体实现中，作为一种实施例，处理器40可以包括一个或多个CPU。
存储器50可以是只读存储器(read-only memory，ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory，RAM)或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(Electrically Erasable Programmable Read-Only Memory，EEPROM)、只读光盘(Compact Disc Read-Only Memory，CD-ROM))或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。存储器50可以是独立存在。存储器50也可以和控制器40集成在一起。可以用于存储光伏组串300的电流、电压及功率等数据。
本申请实施例中，存储器50还用于存储执行本申请方案的应用程序代码，并由控制器40来控制执行。也即，所述控制器50用于执行所述存储器40中存储的应用程序代码。
可以理解的是，本申请实施例示意的结构并不构成对变换器100的具体限定。在本申请另一些实施例中，变换器100可以包括比图示更多或更少的部件，或者组合某些部件，或者拆分某些部件，或者不同的部件布置。图示的部件可以以硬件，软件或软件和硬件的组合实现。
本申请实施例中的变换器100还可以用于对与其相连的光伏组串300进行IV曲线扫描，以检测与其相连的光伏组串300是否存在缺陷或损坏。另外，IV曲线还能指示光伏组串300当前的发电能力、工作状况等信息。然而，光伏组串的IV输出特性受光照变化影响较大，如果光伏系统在对光伏组串进行IV曲线扫描的过程中有光照的变化，会使得检测得到的光伏组串的IV曲线将不能准确反映光伏组串的IV输出特性。
为了能够判断当前所扫描的IV曲线是否有效，是否受到光照变化的影响，本申请实施例还公开一种光伏组串的参数曲线扫描方法，该方法应用于前述的变换器100中。所述参数曲线包括电流电压IV曲线或者功率电压PV曲线中的一种。本申请各实施例中以IV曲 线为例进行说明。
请参阅图4，图4为本申请一实施例中的光伏组串的IV曲线扫描方法的流程图。如图4所示，该光伏组串的IV曲线扫描方法包括如下步骤。
步骤S11，控制光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至第一电压范围的第二端点电压，并在光伏组串的输出电压变化的过程中对光伏组串的输出电流进行采样，以获得第一IV曲线。
其中，第一电压范围是指在进行第一IV曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的电压扫描范围。例如，光伏组串的最大输出电压可以是开路电压，最小输出电压值可以是0V。
在一实施方式中，第一预设规律为固定压差的电压下降规律或者压差变化的电压下降规律中的至少一种。在具体的实际应用中，变换器100控制该光伏组串300的输出电压从开路电压变化至预设最小值的预设规律可以是以固定的电压差(例如25V)来逐渐降低，或者以压差变化的电压下降规律来逐渐降低。该压差变化的电压下降规律具体是指在靠近光伏组串开路电压或者预设最小值附近电压下降较快，而在中间部分电压下降较慢。在其他实施方式中，第一预设规律还可以是其他可以实现电压变化的规律，此处不做具体限定。
步骤S12，控制光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至第二电压范围的第四端点电压，在光伏组串的输出电压变化的过程中对光伏组串的输出电流进行采样，以获得第二IV曲线；第一电压范围和第二电压范围存在交集。
其中，第二电压范围是指在进行第二IV曲线扫描的过程中由光伏组串的最大输出电压和最小输出电压所形成的电压扫描范围。例如，光伏组串的最大输出电压可以是开路电压，最小输出电压可以是0V。第二预设规律与第一预设规律类似，在此不再赘述。
上述图4所示的方法步骤具体的可以由图3所示的变换器100实现。示例的，步骤S11和步骤是12都可以由DC/DC电路10和采样电路30来实现。例如，DC/DC电路10主动调整光伏组串300对应的输入功率，进而控制该光伏组串300的输出电压到相应的端点电压。
本申请实施例所公开的光伏组串的IV曲线扫描方法，由于对光伏组串分别进行第一电压范围和第二电压范围的IV曲线扫描，且第一电压范围和第二电压范围存在交集，进而使得获取的第一IV曲线和第二IV曲线存在电压相同的部分，而该相同的电压所对应的电流由于是在不同时间获得的，因此通过对该相同电压部分所对应的电流进行比对即可确定当前所获得的IV曲线是否存在光照影响，进而可以判断当前所获得的IV曲线是否有效，提高了扫描的可靠性。此外，该方法无需外加测试设备，有效减少了需要提供的硬件设备，降低了曲线扫描的成本。
请参阅图5，图5为本申请另一实施例中的光伏组串的IV曲线扫描方法的流程图。较之于图4，不同的是，本实施方式中的IV曲线扫描方法还包括如下步骤。
步骤S13，判断是否接收到IV曲线扫描指令。若是，则执行步骤S11；若否，则继续执行步骤S13。
由于变换器100初始为正常并网状态，因此只有在变换器100接收到上位机发送的IV曲线扫描指令时才确定需要执行IV曲线扫描任务。也即，本实施方式中，在执行步骤S11 之前还需执行步骤S13。
步骤S14，根据第一IV曲线和第二IV曲线判断当前所扫描的IV曲线是否受到光照变化的影响。若否，则执行步骤S15；若是则执行步骤S16。
本申请实施例中，通过对第一IV曲线和第二IV曲线的对比可以确定当前扫描的IV曲线是否受到光照变化的影响。例如，控制器40将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一IV曲线所对应的光照强度和所述二IV曲线所对应的光照强度是否发生改变。具体的，若第一IV曲线和第二IV曲线在相同的电压点对应的电流值的差值的绝对值小于预设阈值，则控制器40确定当前的IV曲线未受到光照影响，也即当前所获取的IV曲线是有效的。
需要说明的是，在理想环境下，若光照未强度发生变化，光伏组串300在相同输出电压下的电流应是相同的。但是在实际使用过程中，由于采样精度会导致相同电压下的两次采样电流可能会存在些许误差，或者，虽然在两次电流的采样过程中光照会有些许变化，但可视为不存在光照变化，因此只要在相同电压下的两次采样电流的差值的绝对值在允许范围内，即可确定当前所获取的IV曲线未受到光照变化的影响。而预设阈值可以根据实际应用情况而确定，在此不做限定。
步骤S15，对所述第一IV曲线和所述第二IV曲线进行处理，以得到最终的IV曲线。
当确定当前所获取的第一IV曲线和所述第二IV曲线未受到光照变化的影响时，说明所述第一IV曲线和所述第二IV曲线均是有效的，但是为了进一步提高所获得曲线的精度，可以对第一IV曲线和所述第二IV曲线进行综合处理，例如对相同电压点所对应的电流取均值电流，进而获得最终的IV曲线并发送给上位机。
步骤S16，发出异常信号。
当确定当前所获取的第一IV曲线和所述第二IV曲线受到光照变化的影响时，说明第一IV曲线和所述第二IV曲线失效，因此发送异常信号至上位机以表示当前扫描失败。如此，上位机可以根据反馈确定是否从新发送参数曲线扫描指令。
在一种实施方式中，所述第一端点电压大于所述第二端点电压，即所述第一端点电压为第一电压范围的上限电压，而第二端点电压为第一电压范围的下限电压。所述第三端点电压小于所述第四端点电压，即所述第三端点电压为第二电压范围的下限电压，而第四端点电压为第二电压范围的上限电压。也即，先控制光伏组串300的输出电压从第一电压范围的上限电压按照第一预设规律变化至所述第一电压范围的下限电压，以实现第一IV曲线的扫描；再控制所述光伏组串300的输出电压从第二电压范围的下限电压按照第二预设规律变化至所述第二电压范围的上限电压，以实现第二IV曲线的扫描。如此，第一IV曲线扫描的终点和第二IV曲线扫描的起点比较靠近，进而可以提高IV曲线扫描的速度。
具体地，为了体现光伏组串的完整的输出特性，第一电压范围的上限电压设置为小于等于组串开路电压Voc，并且大于组串最大功率点电压Vmpp；实际应用中，第一电压范围的上限电压可以为接近并略小于组串开路电压。第一电压范围的下限电压设置为大于等于零，并且小于组串最大功率点电压Vmpp，实际应用中，第一电压范围的下限电压可以为接近并略大于零。
同理，第二电压范围的上限电压设置为小于等于组串开路电压Voc，并且大于组串最 大功率点电压Vmpp；实际应用中，第二电压范围的上限电压可以为接近并略小于组串开路电压。第二电压范围的下限电压设置为大于等于零，并且小于组串最大功率点电压Vmpp；实际应用中，第二电压范围的下限电压可以为接近并略大于零。
其中，第二电压范围的上限电压可以等于第一电压范围的上限电压，也可以不等于第一电压范围的上限电压；第二电压范围的下限电压可以等于第一电压范围的下限电压，也可以不等于第一电压范围的下限电压。
一种实施方式中，为了提高比对的精度，所述第一电压范围的上限电压和所述第二电压范围的上限电压相等，且所述第一电压范围的下限电压和所述第二电压范围的下限电压相等。也即，所述第一电压范围和第二电压范围完全重合。
另外，在具体的实施方式中，为了方便对第一IV曲线和第二IV曲线的比对，提高比对效率，所述第一预设规律和第二预设规律均为固定压差的电压变化规律。本申请实施例中，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律。例如，可以在第一电压范围和第二电压范围分别取32个采样点。第一电压范围的上限电压为光伏组串300的开路电压Voc，第一电压范围的下限电压为0V。则第一电压范围的32个采样点分别为，U1＝Voc，U2＝(30/31)*Voc，U3＝(29/31)*Voc…U31＝(1/31)*Voc，U32＝0。同理，第二电压范围的32个采样点则分别为U1＝0，U2＝(1/31)*Voc，U3＝(2/31)*Voc…U31＝(30/31)*Voc，U32＝Voc。如此，第一电压范围的采样点和第二电压范围的采样点完全相同，减少了运算量，提高了比对的速度。
请参阅图6，图6为本申请一实施例中的光伏组串的IV扫描波形图。为了进一步提高比对的效率，使得两次的采样点数据完全相同，如图6所示，所述第一电压范围关于时间的波形F1与所述第二电压范围关于时间的波形F2对称。其中，a1为第一电压范围的上限电压，b1为第一电压范围的下限电压；c1为第二电压范围的下限电压，d1为第二电压范围的上限电压。
在另一种实施方式中，所述第一端点电压小于所述第二端点电压，即所述第一端点电压为第一电压范围的下限电压，而第二端点电压为第一电压范围的上限电压。所述第三端点电压大于所述第四端点电压，即所述第三端点电压为第二电压范围的上限电压，而第四端点电压为第二电压范围的下限电压。也即，先控制光伏组串300的输出电压从第一电压范围的下限电压按照第一预设规律变化至所述第一电压范围的上限电压，以实现第一IV曲线的扫描；再控制所述光伏组串300的输出电压从第二电压范围的上限电压按照第二预设规律变化至所述第二电压范围的下限电压，以实现第二IV曲线的扫描，其他细节则与前述实施例相同或类似，在此不再赘述。
本申请实施方式中的IV扫描波形如图7所示，所述第一电压范围关于时间的波形F3与所述第二电压范围关于时间的波形F4对称。其中，a2为第一电压范围的下限电压，b2为第一电压范围的上限电压；c2为第二电压范围的上限电压，d2为第二电压范围的下限电压。
请参阅图8，图8为本申请一实施例中的变换器的功能模块图。在本实施例中，变换器100是以功能单元的形式来呈现。这里的“单元”可以指特定应用集成电路，执行一个或多个软件或固件程序的控制器和存储器，集成逻辑电路，和/或其他可以提供上述功能的 器件。在一个简单的实施例中，本领域的技术人员可以想到变换器100可以采用图8所示的形式。具体的，如图8所示，变换器100包括调节单元101、获取单元102、判断单元103及处理单元104。
所述调节单元101用于控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压。获取单元102用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流，以实现第一IV曲线的扫描。
所述调节单元101还用于控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压。所述获取单元102还用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流，以实现第二IV曲线的扫描。
所述判断单元103用于根据所述第一IV曲线和所述第二IV曲线判断当前所扫描的参数曲线是否受到光照变化的影响。具体地，所述判断单元103用于在所述第一IV曲线和第二IV曲线在相同的电压点所述对应的电流值的差值的绝对值小于预设阈值时，确定当前所扫描的IV曲线未受到光照变化的影响。
所述处理单元104用于在确定当前所扫描的曲线未受到光照变化影响时，对所述第一IV曲线和所述第二IV曲线进行处理，以得到最终的IV曲线。所述处理单元104还用于在确定当前所扫描的曲线受到光照变化影响时，发出异常信号。
在具体的实现中，示例地，调节单元101可以通DC/DC电路101来实现。获取单元102可以由采样电路20实现，判断单元103和处理单元104可以由控制器50实现。
本申请实施例还提供了一种计算机存储介质，用于储存为上述图8所示的变换器所用的计算机软件指令，其包含用于执行上述方法实施例所设计的程序。通过执行存储的程序，可以实现光伏组串的IV曲线扫描，并进一步确定是否受到光照变化的影响。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的装置和各个单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理包括，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用硬件加软件功能单元的形式实现。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的方法而言，由于其与实施例公开的装置相对应，所以描述的比较简单，相关之处参见装置部分说明即可。
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，本申请并不受所描述的动作顺序的限制，因为依据本申请，某一些步骤可以采用其他顺序或者同时进行。
本申请实施例方法中的步骤可以根据实际需要进行顺序调整、合并和删减。
本申请的各实施方式可以任意进行组合，以实现不同的技术效果。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产 品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线)或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘Solid State Disk)等。
总之，以上所述仅为本发明技术方案的实施例而已，并非用于限定本发明的保护范围。凡根据本发明的揭露，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (17)

  1. 一种光伏组串的参数曲线扫描方法，应用于光伏发电系统中，所述光伏发电系统包括变换器及与所述变换器相连的至少一个光伏组串；其特征在于，所述扫描方法包括：
    控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压，并在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流或功率参数，以实现第一参数曲线的扫描；
    控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压，并在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流或功率参数，以实现第二参数曲线的扫描；所述第一电压范围和所述第二电压范围存在交集。
  2. 如权利要求1所述的扫描方法，其特征在于，所述第一端点电压大于所述第二端点电压且所述第三端点电压小于所述第四端点电压；或者，所述第一端点电压小于所述第二端点电压且所述第三端点电压大于所述第四端点电压。
  3. 如权利要求2所述的扫描方法，其特征在于，所述第一端点电压等于所述第四端点电压，和/或，所述第二端点电压等于所述第三端点电压。
  4. 如权利要3所述的扫描方法，所述第一电压范围关于时间的波形与所述第二电压范围关于时间的波形对称。
  5. 如权利要求1所述的扫描方法，其特征在于，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律；或者，所述第一预设规律为固定压差的电压上升规律，且所述第二预设规律为固定压差的电压下降规律。
  6. 如权利要求1-5任一项所述的扫描方法，其特征在于，所述扫描方法还包括：
    根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响。
  7. 如权利要求6所述的扫描方法，其特征在于，所述根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响，包括：
    将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一参数曲线所对应的光照强度和所述二参数曲线所对应的光照强度是否发生改变。
  8. 如权利要求6或7所述的扫描方法，其特征在于，所述扫描方法还包括：
    若所述第一参数曲线和第二参数曲线在相同的电压点所述对应的参数值的差值的绝对值小于预设阈值，确定当前所扫描的参数曲线未受到光照变化的影响。
  9. 一种变换器，其特征在于，包括：
    DC/DC电路，用于控制所述光伏组串的输出电压从第一电压范围的第一端点电压按照第一预设规律变化至所述第一电压范围的第二端点电压；以及
    采样电路，用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第一参数曲线的扫描；
    所述DC/DC电路还用于控制所述光伏组串的输出电压从第二电压范围的第三端点电压按照第二预设规律变化至所述第二电压范围的第四端点电压；
    所述采样电路还用于在所述光伏组串的输出电压变化的过程中获取所述光伏组串的电流参数和/或功率参数，以实现第二参数曲线的扫描；所述第一电压范围和所述第二电压范围存在交集。
  10. 如权利要求9所述的变换器，其特征在于，所述第一端点电压大于所述第二端点电压且所述第三端点电压小于所述第四端点电压；或者，所述第一端点电压小于所述第二端点电压且所述第三端点电压大于所述第四端点电压。
  11. 如权利要求10所述的变换器，其特征在于，所述第一端点电压等于所述第四端点电压，和/或，所述第二端点电压等于所述第三端点电压。
  12. 如权利要求11所述的变换器，其特征在于，所述第一电压范围关于时间的波形与所述第二电压范围关于时间的波形对称。
  13. 如权利要求9所述的变换器，其特征在于，所述第一预设规律为固定压差的电压下降规律，且所述第二预设规律为固定压差的电压上升规律；或者，所述第一预设规律为固定压差的电压上升规律，且所述第二预设规律为固定压差的电压下降规律。
  14. 如权利要求9-13任一项所述的变换器，其特征在于，所述变换器还包括控制器；所述控制器分别与所述采样电路和所述DC/DC电路电连接；所述控制器用于根据所述第一参数曲线和所述第二参数曲线判断当前所扫描的参数曲线是否受到光照变化的影响。
  15. 如权利要求14所述的变换器，其特征在于，所述控制器用于将所述第一参数曲线和所述第二参数曲线进行比对，以判断所述第一参数曲线所对应的光照强度和所述二参数曲线所对应的光照强度是否发生改变。
  16. 如权利要求14或15所述的变换器，其特征在于，所述控制器用于在所述第一参数曲线和第二参数曲线在相同的电压点所述对应的参数值的差值的绝对值小于预设阈值时，确定当前所扫描的参数曲线未受到光照变化的影响。
  17. 一种光伏发电系统，包括电网和至少一个光伏组串；其特征在于，所述光伏发电系统还包括如权利要求9-13任一项所述的变换器；所述变换器的输入端连接所述至少一个光伏组串，且所述变换器的输出端连接所述电网。
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