WO2024041110A1 - 一种光伏发电系统和光伏发电系统的控制方法 - Google Patents

一种光伏发电系统和光伏发电系统的控制方法 Download PDF

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Publication number
WO2024041110A1
WO2024041110A1 PCT/CN2023/099663 CN2023099663W WO2024041110A1 WO 2024041110 A1 WO2024041110 A1 WO 2024041110A1 CN 2023099663 W CN2023099663 W CN 2023099663W WO 2024041110 A1 WO2024041110 A1 WO 2024041110A1
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voltage
power
frequency
grid
output
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Ceased
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PCT/CN2023/099663
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English (en)
French (fr)
Inventor
张美清
董明轩
于心宇
辛凯
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Huawei Digital Power Technologies Co Ltd
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Huawei Digital Power Technologies Co Ltd
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Priority to EP23856202.9A priority Critical patent/EP4572071A4/en
Publication of WO2024041110A1 publication Critical patent/WO2024041110A1/zh
Priority to US19/059,590 priority patent/US20250192566A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/001—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies
    • H02J3/0014—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies for preventing or reducing power oscillations in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/001—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies
    • H02J3/0014—Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies for preventing or reducing power oscillations in networks
    • H02J3/00142—Oscillations concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/46—Controlling the sharing of generated power between the generators, sources or networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2101/00—Supply or distribution of decentralised, dispersed or local electric power generation
    • H02J2101/20—Dispersed power generation using renewable energy sources
    • H02J2101/22—Solar energy
    • H02J2101/24—Photovoltaics
    • 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 field of photovoltaics, and in particular, to a photovoltaic power generation system and a control method of the photovoltaic power generation system.
  • This application provides a photovoltaic power generation system and a control method of the photovoltaic power generation system, which can achieve rapid frequency support.
  • embodiments of the present application provide a photovoltaic power generation system, including a DC converter, an inverter and an inverter controller.
  • the DC converter is used to connect the output of the photovoltaic module to perform voltage conversion on the DC power output by the photovoltaic module;
  • the inverter is used to convert the DC power output by the DC converter into AC power and output it to the power grid;
  • the first controller is used to convert the DC power output by the DC converter according to the output of the DC converter.
  • the first driving signal is generated from two of the first voltage of the direct current, the active power output by the inverter and the operating parameters of the power grid, and the operating state of the inverter is controlled according to the first driving signal.
  • the first voltage is the voltage amplitude of the DC power output by the DC converter, and the operating parameters of the power grid include one or more of reactive current, active current, reactive power, active power, voltage amplitude and power grid frequency.
  • the first controller detects that the power grid deviates from its normal operating rated frequency, it can use any two of the above three parameters to generate the corresponding drive signal and adjust the operating status of the inverter, so that the inverter The AC output from the converter can realize the frequency support function.
  • the first controller is specifically configured to: generate a first active power control signal according to the first voltage difference and the first frequency difference; and generate a first active power control signal according to the first active power control signal and the operating parameters of the power grid, Generate a first drive signal.
  • the first voltage is the voltage amplitude of the DC power output by the DC converter, and the operating parameters of the power grid include one or more of reactive current, active current, reactive power, active power, voltage amplitude and power grid frequency.
  • droop control between the active power output by the inverter and the DC voltage can be performed according to the first voltage difference between the first voltage and the first reference voltage, and the inverter can be performed according to the frequency difference.
  • the droop control between the output active power and the grid frequency is used, and the above two droop control strategies are used to jointly determine the active power value used to achieve frequency support.
  • the first controller is specifically configured to: generate a first modulated wave signal according to the first active power control signal and the operating parameters of the power grid; generate a first modulated wave signal according to the first modulated wave signal and the first carrier signal.
  • Driving signal wherein the first carrier signal is a sine wave signal or a pulse signal with a fixed period.
  • the first carrier signal is adjusted through the first modulated wave signal used to control the output power of the inverter to obtain the first drive signal used to control the conduction timing of the switching tube in the inverter, thereby Adjust the active power value output by the inverter.
  • the first controller is specifically configured to: obtain the first power value using the first voltage difference and the first droop coefficient; the first droop coefficient is based on the DC power output by the DC converter and the inverter output. The corresponding relationship between the active power is determined; the second power value is obtained by using the first frequency difference and the second droop coefficient; the second droop coefficient is determined based on the corresponding relationship between the grid frequency and the active power output by the inverter. ; Generate a first active power control signal according to the first power value, the second power value and the third power value.
  • the third power value is the initial value of active power issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the corresponding relationship between the grid frequency and the active power output by the inverter, and the corresponding relationship between the DC voltage output by the DC converter and the active power output by the inverter select an appropriate droop curve, thereby improving Frequency support effect.
  • the first controller is also used to: obtain the power grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first drive signal; and determine the current and adjacent acquisitions.
  • the first driving signal is adjusted to increase the active power output by the photovoltaic power generation system.
  • the photovoltaic The active power output by the power generation system is less than or equal to the first set value, and the first set value is the maximum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the active power output by the DC converter to the inverter increases, which can be controlled without affecting the operation of the grid.
  • the active power output by the photovoltaic power generation system increases.
  • the first controller is also used to: obtain the power grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first drive signal; and determine the current and adjacent acquisitions.
  • the first driving signal is adjusted to reduce the active power output by the photovoltaic power generation system.
  • the photovoltaic power generation The active power output by the system is greater than or equal to the second set value, and the second set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the active power output by the photovoltaic power generation system increases.
  • the active power output by the photovoltaic power generation system decreases.
  • the active power output of the photovoltaic power generation system can be controlled to decrease.
  • the first controller is specifically configured to: generate a first voltage control signal based on the first power difference and the second frequency difference; generate a third voltage control signal based on the first voltage control signal and the operating parameters of the power grid.
  • a driving signal is the first power difference.
  • the first power difference is the difference between the active power output by the inverter and the first reference power
  • the second frequency difference is the difference between the grid frequency and the second reference frequency
  • the first reference power is The rated active power value output by the inverter when the power grid is operating normally
  • the first reference frequency is the rated frequency value when the power grid is operating normally.
  • droop control between the active power output by the inverter and the DC side voltage can be performed based on the first power difference value, and droop control between the grid frequency and the DC side voltage can be performed based on the second frequency difference value.
  • droop control strategies to jointly determine the DC voltage amplitude used to control the inverter drive signal, and achieve rapid frequency support by controlling the inverter drive signal.
  • the first controller is specifically configured to: generate a second modulated wave signal according to the first voltage control signal and the operating parameters of the power grid; generate a first drive signal according to the second modulated wave signal and the second carrier signal. signal, wherein the second carrier signal is a sine wave signal or a pulse signal with a fixed period.
  • the second carrier signal is adjusted through the second modulated wave signal used to control the output power of the inverter to obtain the first drive signal used to control the conduction timing of the switching tube in the inverter, thereby Adjust the output parameters of the inverter.
  • the first controller is specifically configured to obtain the first DC voltage value using the first power difference and the third droop coefficient; the third droop coefficient is based on the active power output by the DC converter and the DC converter The corresponding relationship between the output DC power is determined; the second DC voltage value is obtained using the second frequency difference and the fourth droop coefficient; the fourth droop coefficient is determined based on the corresponding relationship between the grid frequency and the DC power output by the DC converter. ; generate a first voltage control signal according to the first DC voltage value, the second DC voltage value and the third DC voltage value, where the third DC voltage value is the initial DC voltage value issued by the power station management system, and the power station management system Used to control the operating status of photovoltaic power generation systems.
  • the corresponding relationship between the grid frequency and the first voltage output by the DC converter and the corresponding relationship between the active power output by the inverter and the first voltage output by the DC converter select an appropriate droop curve, Thereby improving the frequency support effect.
  • the first controller is also used to: obtain the power grid frequency and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first driving signal;
  • the first drive signal is adjusted to increase the first voltage output by the DC converter, and
  • the active power output by the photovoltaic power generation system is reduced.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the third set value, and the third set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the active power output by the photovoltaic power generation system exceeds the power demand of the grid.
  • the active power output by the photovoltaic power generation system can be controlled to decrease.
  • the first controller is also used to: obtain the power grid frequency and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first driving signal; When the frequency of the grid obtained in adjacent times is the same and the active power voltage of the inverter output obtained this time is greater than the active power output of the inverter obtained last time, the first driving signal is adjusted so that the DC converter outputs the third The voltage increases and the active power output by the photovoltaic power generation system decreases. After adjusting the first driving signal, the active power output by the photovoltaic power generation system is greater than or equal to the fourth set value. The fourth set value is when the power grid is operating normally. The minimum active power output by the photovoltaic power generation system.
  • the first drive signal can be adjusted to control the active power output from the photovoltaic power generation system. power reduction to achieve smooth operation of the power grid.
  • the first controller is specifically configured to: generate a first frequency control signal according to the second power difference and the second voltage difference; generate a first frequency control signal according to the first frequency control signal and the operating parameters of the power grid.
  • a driving signal is the difference between the active power output by the inverter and the second reference power
  • the second voltage difference is the difference between the first voltage and the second reference voltage
  • the second reference power is the rated active power value output by the inverter when the power grid is operating normally
  • the second reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally.
  • the droop control between the grid frequency and the active power output by the inverter can be performed based on the second power difference value, and the droop control between the grid frequency and the first voltage output by the DC converter can be performed based on the second voltage difference value.
  • the above two droop control strategies are used to jointly determine the frequency of the inverter output, and the frequency support effect is achieved by adjusting the frequency of the inverter output.
  • the first controller is specifically configured to: generate a third modulated wave signal according to the first frequency control signal and the operating parameters of the power grid; generate the first drive signal according to the third modulated wave signal and the third carrier signal. signal, wherein the third carrier signal is a sine wave signal or a pulse signal with a fixed period.
  • the third carrier signal is adjusted through the third modulated wave signal used to control the output power of the inverter to obtain the first drive signal used to control the conduction timing of the switching tube in the inverter, thereby Adjust the output parameters of the inverter.
  • the first controller is specifically configured to generate a first frequency value using the second power difference and the fifth droop coefficient.
  • the fifth droop coefficient is based on the active power output by the inverter and the grid frequency.
  • the second frequency value is generated using the second voltage difference and the sixth droop coefficient.
  • the sixth droop coefficient is determined based on the corresponding relationship between the DC power output by the DC converter and the grid frequency; according to The first frequency value, the second frequency value and the third frequency value generate a first frequency control signal.
  • the third frequency value is the initial frequency value issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the corresponding relationship between the grid frequency and the active power output by the inverter and the corresponding relationship between the first voltage output by the DC converter and the grid frequency select an appropriate droop curve, thereby improving the frequency support effect.
  • the first controller is also used to: obtain the first voltage and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first driving signal;
  • the first drive signal is adjusted to increase the frequency of the alternating current output by the inverter.
  • the active power output by the photovoltaic power generation system increases.
  • the active power output by the photovoltaic power generation system is less than or equal to the fifth set value, and the grid frequency is less than or equal to the maximum frequency value during normal operation of the power grid.
  • the fifth set value is the normal operation of the power grid.
  • the maximum active power output by the photovoltaic power generation system is also used to: obtain the first voltage and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first driving signal;
  • the active power output by the DC converter to the inverter increases, and the active power output by the photovoltaic power generation system can be controlled without affecting the operation of the power grid. Power goes up.
  • the first controller is also used to: obtain the first voltage and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first driving signal; When the first voltage obtained adjacently is the same and the active power output by the inverter obtained this time is greater than the active power output by the inverter obtained previously, the first driving signal is adjusted so that the inverter output The frequency of alternating current decreases, and the active power output by the photovoltaic power generation system decreases.
  • the active power output by the photovoltaic power generation system is greater than or equal to the sixth set value, and the grid frequency is greater than or equal to the minimum frequency value during normal operation of the grid.
  • the sixth set value is the normal operation of the grid. The minimum active power output by the photovoltaic power generation system.
  • the photovoltaic power generation system also includes a second controller connected to the DC converter for rooting A second driving signal is generated according to the third voltage difference, and the active power output by the DC converter is controlled according to the second driving signal.
  • the third voltage difference is the difference between the third reference voltage and the first voltage, and the third reference voltage is the rated voltage output by the DC converter when the power grid is operating normally.
  • the inverter since the inverter is connected to the DC converter, that is, the active power output by the inverter is mainly provided by the DC converter. In order to realize that the inverter can output active power for frequency support, it can be through the DC converter.
  • the controller adjusts the active power output by the DC converter so that the output active power meets the frequency support requirements.
  • the second controller can directly determine the grid frequency condition through the first voltage, there is no need to obtain the grid frequency through a high-speed transmission line, which speeds up the frequency support of the photovoltaic power generation system.
  • the second controller is specifically used to: determine the working mode of the DC converter, which includes a one-way support mode and a two-way support mode; generate The third reference voltage, the operating parameters of the DC converter include one or more of input current, input voltage and input power; according to the third voltage difference and the seventh droop coefficient, the fourth power value is obtained, and the seventh droop coefficient is Determined according to the corresponding relationship between the output voltage of the DC converter and the active power output by the DC converter; according to the fourth power value and the maximum power value, the second active power control signal is determined; according to the second active power control signal and the DC The input parameters of the converter generate the second drive signal.
  • the output voltage of the DC converter rises.
  • the output voltage of the DC converter drops. Therefore, the voltage output by the DC converter can be compared with the reference voltage. The second voltage difference between them determines the current power grid situation and makes corresponding power adjustments to achieve frequency support.
  • the second controller is also used to calculate the maximum power value MPPE according to the operating parameters of the DC converter.
  • the DC converter will operate in the MPPT mode without frequency support and output the maximum power value.
  • MPPE can be used to estimate the maximum power value and calculate the maximum power value at the maximum Power adjustment is performed based on the power value.
  • the second controller is specifically configured to: determine the additional reserved power value according to the operating mode of the DC converter; and generate the third reference voltage according to the operating parameters of the DC converter and the additional reserved power value.
  • the output power of the DC converter can be determined based on the operating parameters of the DC converter and the set additional reserved power value, thereby dynamically adjusting the reference voltage value.
  • embodiments of the present application provide a control method for a photovoltaic power generation system.
  • the method can be applied to the photovoltaic power generation system. It specifically includes the following steps: monitoring the operating parameters of the power grid, the first voltage output by the inverter and the DC The active power output by the converter; generate a first driving signal according to two of the first voltage, the active power output by the DC converter and the operating parameters of the power grid, and control the operating state of the inverter according to the first driving signal, where , the first voltage is the voltage amplitude of the DC power output by the DC converter, and the operating parameters of the power grid include one or more of reactive current, active current, reactive power, active power, voltage amplitude and power grid frequency.
  • the first driving signal is generated based on two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: based on the first voltage difference and the first frequency difference. , generate the first active power control signal, where the first voltage difference is the difference between the first voltage and the first reference voltage, and the first frequency difference is the difference between the grid frequency and the first reference frequency,
  • the first reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally
  • the first reference frequency is the rated frequency value when the power grid is operating normally
  • the first driving signal is generated according to the first active power control signal and the operating parameters of the power grid.
  • generating the first driving signal according to the first active power control signal and the operating parameters of the power grid includes: generating the first modulated wave signal according to the first active power control signal and the operating parameters of the power grid; A modulated wave signal and a first carrier wave signal generate a first drive signal, wherein the first carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating a first active power control signal according to the first voltage difference and the first frequency difference includes: using the first voltage difference and the first droop coefficient to obtain the first power value; The droop coefficient is determined based on the corresponding relationship between the DC voltage output by the DC converter and the active power output by the DC converter; the second power value is obtained by using the first frequency difference and the second droop coefficient; the second droop coefficient is based on The corresponding relationship between the grid frequency and the active power output by the inverter is determined; according to the first power value, the second power value and the third power value, a first active power control signal is generated, where the third power value is The initial value of active power issued by the management system is used by the power station management system to control the operating status of the photovoltaic power generation system.
  • the method also includes: obtaining the grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first drive signal; and determining the grid frequency obtained this time and the adjacent time. are the same, and when the first voltage obtained this time is greater than the first voltage obtained last time, the first driving signal is adjusted to increase the active power output by the photovoltaic power generation system. After adjusting the first driving signal, the output of the photovoltaic power generation system The active power is less than or equal to the first set value, and the first set value is the maximum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the method further includes: obtaining the grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first driving signal; and determining the first frequency obtained this time and the adjacent time.
  • the first driving signal is adjusted to reduce the active power output by the photovoltaic power generation system.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the second set value, and the second set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first driving signal is generated based on two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: based on the first power difference and the second frequency difference.
  • generate a first voltage control signal where the first power difference is the difference between the active power output by the inverter and the first reference power, and the second frequency difference is the difference between the grid frequency and the second reference frequency.
  • the first reference power is the rated active power value output by the inverter when the power grid is operating normally
  • the first reference frequency is the rated frequency value when the power grid is operating normally
  • the first reference power is generated A driving signal.
  • generating the first driving signal according to the first voltage control signal and the operating parameters of the power grid includes: generating a second modulated wave signal according to the first voltage control signal and the operating parameters of the power grid; wave signal and a second carrier wave signal to generate a first driving signal, wherein the second carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating the first voltage control signal according to the first power difference and the second frequency difference includes: using the first power difference and the third droop coefficient to obtain the first DC voltage value; The droop coefficient is determined based on the corresponding relationship between the active power output by the DC converter and the DC power output by the DC converter; the second DC voltage value is obtained using the second frequency difference and the fourth droop coefficient; the fourth droop coefficient is based on The corresponding relationship between the grid frequency and the DC output by the DC converter is determined; a first voltage control signal is generated according to the first DC voltage value, the second DC voltage value and the third DC voltage value, wherein the third DC voltage value It is the initial value of DC voltage issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the method also includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the grid frequency and the active power output by the inverter; determining the current time and the adjacent time Obtained inverter output When the active power is the same and the grid frequency obtained this time is greater than the grid frequency obtained last time, the first drive signal is adjusted so that the first voltage output by the DC converter increases and the active power output by the photovoltaic power generation system decreases. .
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the third set value, and the third set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the method also includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the grid frequency and the active power output by the inverter; determining the current time and the adjacent time
  • the first drive signal is adjusted so that the first voltage output by the DC converter increases. large, and the active power output of the photovoltaic power generation system is reduced.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the fourth set value, and the fourth set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first driving signal is generated based on two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: based on the second power difference and the second voltage difference. , generate a first frequency control signal, where the second power difference is the difference between the active power output by the inverter and the second reference power, and the second voltage difference is the difference between the first voltage and the second reference voltage.
  • the difference, the second reference power is the rated active power value output by the inverter when the power grid is operating normally, and the second reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally; according to the first frequency control signal and the power grid's operating parameters to generate the first driving signal.
  • generating the first driving signal according to the first frequency control signal and the operating parameters of the power grid includes: generating a third modulated wave signal according to the first frequency control signal and the operating parameters of the power grid; wave signal and a third carrier wave signal to generate a first driving signal, wherein the third carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating the first frequency control signal according to the second power difference and the second voltage difference includes: using the second power difference and the fifth droop coefficient to generate the first frequency value, and the fifth droop coefficient.
  • the droop coefficient is determined based on the corresponding relationship between the active power output by the inverter and the grid frequency; the second voltage difference and the sixth droop coefficient are used to generate the second frequency value.
  • the sixth droop coefficient is based on the output of the DC converter.
  • the corresponding relationship between the DC power and the grid frequency is determined; according to the first frequency value, the second frequency value and the third frequency value, the first frequency control signal is generated, where the third frequency value is the initial frequency value issued by the power station management system. Frequency value, the power station management system is used to control the operating status of the photovoltaic power generation system.
  • the method further includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the first voltage and the active power output by the inverter; When the active power output by the inverter obtained once is the same and the first voltage obtained this time is greater than the first voltage obtained previously, the first drive signal is adjusted to increase the frequency of the alternating current output by the inverter, and the photovoltaic The active power output by the power generation system increases.
  • the active power output by the photovoltaic power generation system is less than or equal to the fifth set value, and the grid frequency is less than or equal to the maximum frequency value during normal operation of the grid.
  • the fifth setting value is the maximum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the method further includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the first voltage and the active power output by the inverter; When the first voltage obtained once is the same and the active power output by the inverter obtained this time is greater than the active power output by the inverter obtained last time, the first drive signal is adjusted so that the frequency of the alternating current output by the inverter decrease, and the active power output of the photovoltaic power generation system decreases.
  • the active power output by the photovoltaic power generation system is greater than or equal to the sixth set value, and the grid frequency is greater than or equal to the minimum frequency value during normal operation of the grid.
  • the sixth setting value is the normal operation of the power grid. The minimum active power output by the photovoltaic power generation system.
  • the method further includes: generating a second driving signal according to the difference between the first voltage and the third voltage, and controlling the active power output by the DC converter according to the second driving signal, wherein the third voltage
  • the difference is the difference between the third reference voltage and the first voltage
  • the third reference voltage is the rated voltage output by the DC converter when the power grid is operating normally.
  • generating a second driving signal according to the difference between the first voltage and the third voltage includes: determining the working mode of the DC converter, and the working mode includes a one-way support mode and a two-way support mode; according to the DC conversion
  • the third reference voltage is generated by the operating mode of the converter and the operating parameters of the DC converter, and the operating parameters of the DC converter include one or more of the input current and the input power; according to the third voltage difference and the seventh droop coefficient, the third reference voltage is obtained
  • the fourth power value and the seventh droop coefficient are determined based on the corresponding relationship between the output voltage of the DC converter and the active power output by the DC converter; the second active power control signal is determined based on the fourth power value and the maximum power value MPPE. ; Generate a second driving signal according to the second active power control signal and the input parameters of the DC converter.
  • generating the second driving signal according to the second active power control signal and the input parameters of the DC converter includes: generating a fourth modulation signal according to the second active power control signal and the input parameters of the DC converter. wave signal; generate a second driving signal according to the fourth modulated wave signal and the fourth carrier wave signal, where the fourth carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • the method further includes: determining the MPPE according to operating parameters of the DC converter.
  • generating the third reference voltage according to the working mode of the DC converter and the operating parameters of the DC converter includes: determining the additional reserved power value according to the working mode of the DC converter; parameters and additional reserved power values to generate the third reference voltage.
  • Figure 1 is a schematic structural diagram of a photovoltaic power generation system provided by an embodiment of the present application
  • Figure 2 is a schematic structural diagram 2 of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 3 is a schematic diagram of the correspondence between the active power output by an inverter and the DC voltage provided by an embodiment of the present application;
  • Figure 4 is a schematic diagram of the correspondence between the active power output by an inverter and the grid frequency provided by an embodiment of the present application;
  • Figure 5 is a schematic diagram of the correspondence between DC voltage and power grid frequency provided by an embodiment of the present application.
  • Figure 6 is a schematic structural diagram three of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 7 is a schematic diagram 1 of the corresponding relationship between the active power output by a DC converter and the DC voltage provided by an embodiment of the present application;
  • Figure 8 is a schematic diagram 1 of the output waveform of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 9 is a schematic diagram 2 of the output waveform of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 10 is a schematic diagram 2 of the corresponding relationship between the active power output by a DC converter and the DC voltage provided by the embodiment of the present application;
  • Figure 11 is a schematic diagram 3 of the output waveform of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 12 is a schematic diagram 4 of the output waveform of a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 13 is a schematic flow chart 1 of a control method for a photovoltaic power generation system provided by an embodiment of the present application;
  • Figure 14 is a schematic flow chart 2 of a control method for a photovoltaic power generation system provided by an embodiment of the present application;
  • Figure 15 is a schematic flow chart 3 of a control method for a photovoltaic power generation system provided by an embodiment of the present application.
  • Figure 16 is a schematic flow chart 4 of a control method for a photovoltaic power generation system provided by an embodiment of the present application
  • Figure 17 is a schematic flow chart 5 of a control method for a photovoltaic power generation system provided by an embodiment of the present application.
  • the switching transistor in the embodiment of the present application may be a relay, a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), or an insulated gate bipolar
  • MOSFET metal oxide semiconductor field effect transistor
  • BJT bipolar junction transistor
  • IGBT insulated gate bipolar
  • IGBT insulated gate bipolar transistor
  • SiC silicon carbide
  • the packaging form of each switch tube may be a single tube package or a multi-tube package, which is not limited in the embodiment of the present application.
  • Each switch tube may include a first terminal, a second terminal and a control terminal, wherein the control terminal is used to control the switching tube to be turned on or off.
  • the control terminal of the switch tube is the gate.
  • the first terminal of the switch tube can be the source and the second terminal can be the drain. Or, the first terminal can be the drain and the second terminal can be the source.
  • connection can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between two electrical components.
  • a and B can be connected directly, or A and B can be connected indirectly through one or more other electrical components.
  • a and B can be connected, or A and C can be connected directly.
  • C and B are directly connected, and A and B are connected through C.
  • the "connection” in the embodiment of this application can also be understood as a wireless connection, that is, the connection between two electrical components can be an electromagnetic connection between two electrical components.
  • Active power-frequency droop control Using the approximate linear relationship between active power and the frequency of the power grid, active power-frequency droop control can be constructed. Through active power-frequency droop control, when the power grid cannot meet the load demand and the frequency of the power grid fluctuates, the inverter output can be controlled to control the frequency of the power grid to restore normal active power.
  • Voltage-active power droop control establish an approximate linear relationship between the DC voltage at the input side of the inverter and the active power output by the inverter, and use this approximate linear relationship to construct voltage-active power droop control.
  • voltage-active power droop control when the grid cannot meet the load demand and the frequency of the grid fluctuates, the inverter output can be controlled for control. The frequency of the power grid is restored to normal active power.
  • Voltage-frequency droop control establish an approximate linear relationship between the DC voltage and the frequency of the power grid, and use this approximate linear relationship to construct voltage-frequency droop control.
  • DC voltage-frequency droop control when the grid cannot meet the load demand and the frequency of the grid fluctuates, the DC converter can be controlled to output the active power required to restore the grid frequency.
  • the controller of the DC converter can perform maximum power point tracking of the photovoltaic components, which can significantly increase the output power of the photovoltaic array and thereby improve the energy utilization of the photovoltaic system. .
  • the controller of the DC converter can estimate the maximum power point of the photovoltaic module.
  • new energy systems may include but are not limited to: photovoltaic power generation systems, wind power generation systems, hydropower generation systems, etc.
  • the above-mentioned new energy system can be a photovoltaic power generation system.
  • Figure 1 illustrates a schematic structural diagram of a photovoltaic power generation system.
  • the photovoltaic power generation system mainly includes a DC converter, an inverter and a controller. Among them, the photovoltaic power generation system is connected to the photovoltaic components and outputs the electric energy output by the photovoltaic components to the power grid.
  • the photovoltaic power generation system includes photovoltaic components.
  • the photovoltaic modules can convert light energy into DC power;
  • the DC converter is connected to the output end of the photovoltaic module, can receive the DC power output by the photovoltaic module, and perform voltage conversion on the received DC power;
  • the inverter It can receive the voltage-converted DC power output by the DC converter, convert the received DC power into AC power, and output it to the grid through the grid connection point, thereby realizing the grid connection of the photovoltaic power generation system;
  • the controller is connected to the inverter for control
  • the inverter converts the received DC power into AC power.
  • the DC converter is generally connected to the inverter through a DC bus, that is, the voltage amplitude of the DC power output by the DC converter is the DC bus voltage.
  • the inverter is composed of multiple switching devices.
  • the controller controls the conduction state of the multiple switching devices in the inverter by sending drive signals to multiple switches in the inverter, thereby controlling the operation of the inverter. run.
  • the controller is connected to the power station management system on the upper level of the photovoltaic power generation system, and adjusts the operating status of the inverter when receiving control instructions sent by the power station management system.
  • the power station management system can obtain the operating parameters of the power grid regularly or in real time, and monitor the operating status of the power grid.
  • the power station management system can change the frequency of the power grid according to the operating conditions of the power grid.
  • the controller adjusts the active power output by the inverter by adjusting the driving signal of the switching tube in the inverter. value, thereby realizing the frequency support function of the power grid.
  • the frequency support function of the controller is realized through the dispatching instructions issued by the upper-level power station management system.
  • the controller is coordinated and controlled by the power station management system.
  • the response speed is slow.
  • embodiments of the present application provide a photovoltaic power generation system and a control method of the photovoltaic power generation system to quickly achieve frequency support.
  • FIG. 2 is a schematic structural diagram of a photovoltaic power generation system provided by an embodiment of the present application.
  • the photovoltaic power generation system 20 includes a DC converter 21 , an inverter 22 and a first controller 23 .
  • the input end of the DC converter 21 is connected to the output end of the photovoltaic module 24, and the output end of the DC converter 21 is connected to the inverter 22; the inverter 22 is connected to The first controller 23 is connected.
  • the photovoltaic power generation system 20 may also include photovoltaic components 24 .
  • the photovoltaic module 24 can convert light energy into direct current and output the direct current to the DC converter 21; the DC converter 21 can convert the DC power output by the photovoltaic module 24. Perform voltage conversion and output the converted DC power; the inverter 22 can convert the DC power output by the DC converter 21 into AC power and output it to the grid, thereby realizing the grid connection of the photovoltaic power generation system; the first controller 23 communicates with the inverter The inverter 22 is connected, and the inverter 22 can be controlled to convert the received direct current into alternating current. Among them, the DC converter 21 and the inverter 22 are connected through a DC bus.
  • the DC converter 21 is connected to the inverter 22 through a DC bus, and the voltage of the alternating current output by the DC converter 21 is the DC bus voltage.
  • the first controller 23 may generate a first driving signal according to two of the first voltage of the DC power output by the DC converter 21 , the active power output by the inverter 22 and the operating parameters of the power grid, and generate the first driving signal according to the first The driving signal controls the operating state of the inverter 22, so that the alternating current output by the inverter 22 can realize the frequency support function.
  • the operating parameters of the power grid may include one or more of the following: reactive current, active current, active power, reactive power, voltage amplitude and grid frequency.
  • the frequency support calculation can be performed through the first controller 23 local to the photovoltaic power generation system 20. Compared with the upper-level power station management system in the prior art, the frequency support calculation is performed. , reducing the acquisition time of power grid frequency and related parameters and the issuance time of dispatching instructions, thereby achieving fast frequency support and quickly restoring the power grid to a stable state.
  • the photovoltaic power generation system 20 provided by the embodiment of the present application involves the first voltage that represents the output of the photovoltaic power generation system 20 in the frequency support calculation, taking into account the power production of the photovoltaic power generation system 20, without affecting the operation of the power grid.
  • the active power value output by the photovoltaic power generation system 20 can be appropriately increased, thereby increasing the proportion of new energy in the power grid.
  • the inverter 22 may be composed of switching tubes, diodes, inductors, capacitors and other devices.
  • the working status of the inverter 22 can be achieved by adjusting the working status of these devices (such as switching tubes).
  • the first controller 23 can be connected to the gate of the MOS tube to adjust the operation of the inverter 22 by controlling the on and off of the MOS tube;
  • the switching tube in the inverter 22 is a BJT, and the first controller 23 can be connected to the base of the BJT to adjust the operation of the inverter 22 by controlling the on-off state of the BJT.
  • the first controller 23 generates a first driving signal according to the first voltage output by the DC converter 21 and the grid frequency.
  • the first controller 23 can calculate the first voltage difference between the first voltage and the first reference voltage, and calculate the first frequency difference between the grid frequency and the first reference frequency; according to the first voltage difference and the first frequency difference, resulting to generate a first active power control signal; and generate a first driving signal according to the first active power control signal and the current operating parameters of the power grid.
  • the DC converter 21 when the first reference voltage power grid is operating normally, the DC converter 21 outputs a rated voltage value.
  • the first reference frequency is the rated frequency value during normal operation of the power grid.
  • the active power-frequency is established Sagging control strategies.
  • the first voltage output by the DC converter 21 is higher than the first reference voltage, it means that the power output by the DC converter 21 exceeds the rated power value during normal operation of the power grid.
  • the inverter When the inverter sends the above power to the power grid, At this time, the power transmitted on the grid will exceed the actual power demand of the grid.
  • the first voltage output by the DC converter 21 When the first voltage output by the DC converter 21 is lower than the first reference power, it indicates that the power output by the DC converter 21 exceeds the rated power during normal operation of the power grid.
  • the inverter sends the above power to the power grid, the power on the power grid The transmitted power will be less than the power actually required by the grid.
  • a voltage-active power droop control strategy Based on the corresponding relationship between the active power output by the inverter and the DC bus voltage, a voltage-active power droop control strategy is established. The active power value required for frequency support is calculated through the above two droop control strategies.
  • the first controller 23 uses the first voltage difference and the first droop coefficient to form a voltage-active power droop control strategy to obtain the first power value; the first controller 23 uses the first frequency difference and the second droop coefficient.
  • the second power value where the second droop coefficient is determined based on the correspondence between the grid frequency and the active power output by the inverter; the first power value and the second power value obtained by using the above two droop control strategies and a third power value to generate a first active power control signal required for frequency support.
  • the first droop coefficient is determined based on the corresponding relationship between the DC power output by the DC converter and the active power output by the inverter.
  • the third power value is the initial value of active power issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system 20 .
  • the first controller 23 can be connected to a DC sensor and an AC sensor respectively.
  • the DC sensor is used to detect the first voltage output by the DC converter 21
  • the AC sensor can detect the operating parameters of the power grid.
  • the AC detection unit may be, but is not limited to, a voltage sensor and a current sensor. For example, Hall sensors.
  • the following formula can be used to calculate the first active power control signal PINV for power support:
  • K u p is the first droop coefficient
  • K pf is the second droop coefficient
  • U bus is the first voltage
  • f req is the frequency of the power grid
  • P cmd is the initial value of active power issued by the upper-layer power station management system.
  • the first droop coefficient K up and the second droop coefficient K pf may be, but are not limited to, constants, exponents and power exponents.
  • the first droop coefficient is set based on the corresponding relationship curve between the DC bus voltage and the active power output by the inverter 22, and the second droop coefficient is set based on the relationship between the active power output by the inverter and the grid frequency.
  • Corresponding relationship curve settings can be configured through proportional controller, integrator, other combinations or user selection.
  • the first controller 23 uses the above formula 1 to generate a first active power control signal, and uses the first active power control signal and the operating parameters of the current power grid to generate a first modulated wave signal.
  • the first modulated wave signal is consistent with
  • the first carrier signal is compared to generate a first driving signal, which is sent to the switching tube in the inverter 22.
  • the switching tube in the inverter 22 adjusts its conduction timing under the control of the first driving signal, thereby adjusting the inverter.
  • the active power value output by the converter 22 realizes the frequency support function.
  • the first carrier signal may be a sine wave signal with a fixed period or a pulse signal. Number.
  • the active power output by the inverter 22 can be dynamically adjusted by utilizing the dynamic changes of the DC bus voltage and the dynamic changes of the grid frequency.
  • the first controller 23 uses a voltage-active power droop control strategy and an active power-frequency droop control strategy to jointly adjust the active power output by the inverter 22 .
  • a voltage-active power droop control strategy and an active power-frequency droop control strategy to jointly adjust the active power output by the inverter 22 .
  • the DC bus voltage gradually increases within the range of [Ubusmin, Ubusmax], it means that the power generation of the photovoltaic power generation system 20
  • the active power value output by the inverter 22 can be controlled to rise monotonically without affecting the operation of the power grid.
  • the corresponding relationship between the active power output by the inverter 22 and the DC voltage can be seen in Figure 3. Show.
  • the above DC bus voltage range is the operating range of the DC bus when the DC converter 21 is operating normally, and is determined based on the operating voltage of the DC converter 21 and the AC voltage amplitude on the output side of the inverter.
  • the first controller can regularly obtain the power grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first drive signal; after determining that the power grid frequency obtained this time is the same as that obtained at the adjacent time, And when the first voltage obtained this time is greater than the first voltage obtained last time, the first driving signal is adjusted to increase the active power output by the photovoltaic power generation system.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is less than or equal to the first set value
  • the first set value is the maximum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first set value can be configured according to the electrical energy equipment connected to the power grid.
  • the frequency on the grid will rise, and other devices on the grid can reduce the power transmitted to the grid, thereby achieving coordinated control with other devices on the grid.
  • the first controller 23 uses a voltage-active power droop control strategy and an active power-frequency droop control strategy to jointly adjust the active power output by the inverter 22 .
  • a voltage-active power droop control strategy and an active power-frequency droop control strategy to jointly adjust the active power output by the inverter 22 .
  • the active power output by the inverter 22 can be controlled to decrease monotonically.
  • the corresponding relationship between the active power output by the inverter 22 and the grid frequency can be seen in Figure 4 .
  • the above power grid frequency range is the fluctuation range of the power grid during normal operation.
  • the first controller can regularly obtain the power grid frequency and the first voltage in the process of controlling the operating state of the inverter according to the first drive signal; and after determining that the first voltage obtained this time is the same as the first voltage obtained in the adjacent time. , and when the grid frequency obtained this time is greater than the grid frequency obtained previously, the first driving signal is adjusted to reduce the active power output by the photovoltaic power generation system.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the second set value, and the second set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first controller 23 generates a first driving signal according to the active power output by the inverter 22 and the grid frequency.
  • the first controller 23 can generate a first voltage control signal according to the first power difference and the second frequency difference, and generate a first driving signal according to the first voltage control signal and the operating parameters of the power grid.
  • the first power difference is the difference between the active power output by the inverter 22 and the first reference power
  • the second frequency difference is the difference between the grid frequency and the second reference frequency
  • the first reference power is the rated active power value output by the inverter 22 when the power grid is operating normally
  • the first reference frequency is the rated frequency value when the power grid is operating normally.
  • an active power-frequency droop control strategy is established.
  • the DC bus voltage rises, and when the grid frequency is lower than the first reference frequency, the DC bus voltage drops.
  • Establish voltage-frequency droop control strategy is established. The first voltage for frequency support is calculated through the above two droop control strategies.
  • the first controller 23 obtains the first DC voltage value using the first power difference and the third droop coefficient; the third droop coefficient is based on the difference between the active power output by the DC converter 21 and the DC power output by the DC converter 21
  • the second DC voltage value is obtained by using the second frequency difference and the fourth droop coefficient; the fourth droop coefficient is determined according to the corresponding relationship between the grid frequency and the DC output by the DC converter; according to the first
  • the DC voltage value, the second DC voltage value and the third DC voltage value generate a first voltage control signal.
  • the third DC voltage value is the initial value of the DC voltage issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the inverter 22 can operate in the MPPT mode, when the inverter 22 can control the output power of the DC converter by adjusting the output voltage of the DC converter, therefore, when the input voltage of the inverter 22 changes , the voltage output to the grid will also change, thereby achieving frequency support.
  • the first controller 23 may be connected to a first sensor and a second sensor respectively, the first sensor is used to detect the operating parameters of the power grid, and the second sensor is used to detect the active power output by the inverter 22 .
  • the first sensor and the second sensor are both AC sensors, for example, Hall sensors.
  • the first controller 23 uses the dynamic changes of the grid frequency and the dynamic changes of the active power output by the inverter 22 to dynamically adjust the DC voltage on the inverter side. Specifically, the first controller 23 uses the following formula to calculate First voltage control signal for frequency support:
  • f req is the frequency of the power grid, is the reference frequency.
  • the third droop coefficient is determined based on the corresponding relationship between the active power output by the DC converter 21 and the DC power output by the DC converter, and the fourth droop coefficient is determined based on the relationship between the grid frequency and the DC power output by the DC converter 21 The corresponding relationship is determined.
  • the third droop coefficient is set according to the corresponding relationship curve between the DC bus voltage and the active power output by the inverter 22, and the fourth droop coefficient is set according to the relationship between the first voltage output by the DC converter 21 and the grid frequency.
  • the corresponding relationship curve is set.
  • the above values can be configured through proportional controller, integrator, other combinations or user selection.
  • the first controller 23 uses the above formula 2 to generate a first voltage control signal for frequency support, and uses the first voltage control signal and the operating parameters of the current power grid to generate a second modulated wave signal.
  • the modulated wave signal is compared with the second carrier signal to generate a first driving signal, which is sent to the switching tube in the inverter 22.
  • the switching tube in the inverter 22 adjusts its conduction timing under the control of the second driving signal. , thereby adjusting the active power value output by the inverter 22 to realize the frequency support function.
  • the second carrier signal may be a sine wave signal with a fixed period or a pulse signal.
  • the DC voltage output by the DC converter 21 can be dynamically adjusted by utilizing the dynamic change of the grid frequency and the dynamic conversion of the active power output by the inverter.
  • the first controller 23 uses the voltage-active power droop control strategy and the voltage-frequency droop control strategy to jointly adjust the DC voltage received by the inverter 22 .
  • the active power output by the inverter 22 remains unchanged, as the grid frequency gradually increases in the range of [freqmin, freqmax], it means that the active power transmitted on the current grid gradually becomes more and more than the grid.
  • the first voltage amplitude output by the DC converter 21 can be increased, thereby reducing the active power output by the inverter 22 .
  • the first controller can regularly obtain the power grid frequency and the active power output by the inverter according to the first driving signal to control the operating status of the inverter;
  • the first drive signal is adjusted so that the first voltage output by the DC converter increases, and the first voltage output by the photovoltaic power generation system increases.
  • Active power decreases.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the third set value, and the third set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first controller can regularly obtain the power grid frequency and the active power output by the inverter in the process of controlling the operating status of the inverter according to the first drive signal;
  • the first drive signal is adjusted to increase the first voltage output by the DC converter,
  • the active power output by the photovoltaic power generation system increases.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the fourth set value, and the fourth set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first controller 23 may use the first voltage of the DC power output by the DC converter 21 and the active power output by the inverter 22 to generate the first driving signal.
  • the first controller 23 generates a first frequency control signal according to the second power difference and the second voltage difference; and generates a first driving signal according to the first frequency control signal and the operating parameters of the power grid.
  • the second power difference is the difference between the active power output by the inverter and the second reference power
  • the second voltage difference is the difference between the first voltage and the second reference voltage
  • the second reference power is the rated active power value output by the inverter when the power grid is operating normally
  • the second reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally.
  • the active power output by the inverter 22 when the active power output by the inverter 22 is higher than the second reference power, it means that the active power output by the inverter 22 is higher than the active power actually required by the grid, which will cause the frequency of the grid to rise.
  • the active power output by the inverter 22 is lower than the second reference power, it means that the common power output by the inverter 22 is lower than the active power actually required by the grid, which will cause the frequency of the grid to drop.
  • an active power-frequency droop control strategy is established.
  • the first voltage output by the DC converter 21 when the first voltage output by the DC converter 21 is higher than the second reference voltage, it indicates that the power transmitted on the power grid exceeds the power actually required by the power grid, and the frequency of the power grid increases.
  • the first voltage output by the DC converter 21 is lower than the second reference voltage, it indicates that the power transmitted on the grid is lower than the power actually required by the grid, and the frequency of the grid decreases.
  • a voltage-frequency droop control strategy is established, and the frequency used for frequency support is calculated through the above two droop control strategies.
  • the first controller 23 obtains the first DC voltage value using the first power difference and the third droop coefficient; the third droop coefficient is based on the correspondence between the active power output by the DC converter and the DC power output by the DC converter. close system is determined; the second DC voltage value is obtained by using the second frequency difference and the fourth droop coefficient; the fourth droop coefficient is determined based on the corresponding relationship between the grid frequency and the DC output by the DC converter; according to the first DC voltage value, a second DC voltage value and a third DC voltage value to generate a first voltage control signal.
  • the third DC voltage value is the initial value of the DC voltage issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the first controller 23 may be connected to a DC sensor and an AC sensor respectively.
  • the DC sensor is used to detect the first voltage output by the DC converter 21
  • the AC sensor is used to detect the active power output by the inverter 22 .
  • the first controller 23 uses the dynamic changes of the active power output by the inverter 22 and the dynamic changes of the first voltage output by the DC converter 21 to dynamically adjust the frequency of the alternating current output by the inverter 22. Specifically, Ground, the first controller 23 uses the following formula to calculate the first frequency control signal for frequency support:
  • the fifth droop coefficient is determined based on the correspondence between the active power output by the inverter and the grid frequency
  • the sixth droop coefficient is determined based on the correspondence between the DC power output by the DC converter and the grid frequency.
  • the above values can be configured through proportional controller, integrator, other combinations or user selection.
  • the first controller 23 uses the above formula 3 to generate a first frequency control signal for frequency support, and uses the first frequency control signal and the operating parameters of the current power grid to generate a third modulated wave signal.
  • the modulated wave signal is compared with the third carrier signal to generate a first driving signal, which is sent to the switching tube in the inverter 22.
  • the switching tube in the inverter 22 adjusts its conduction timing under the control of the second driving signal. , thereby adjusting the active power value output by the inverter 22 to realize the frequency support function.
  • the third carrier signal may be a sine wave signal with a fixed period or a pulse signal.
  • the frequency of the AC power output by the inverter can be dynamically changed by utilizing the dynamic changes of the first voltage output by the DC converter and the dynamic changes of the active power output by the inverter.
  • the first controller 23 uses the active power-frequency droop control strategy and the voltage-frequency droop control strategy to jointly adjust the DC voltage received by the inverter 22 .
  • Formula 3 it can be seen that when the active power output by the inverter 22 remains unchanged, since the DC converter 21 works in the MPPT mode, as the DC bus voltage gradually increases within the range of [Ubusmin, Ubusmax], it means that the photovoltaic
  • the active power value output by the inverter 22 can be controlled to rise monotonically without affecting the operation of the power grid.
  • the frequency of the alternating current output by the inverter will rise, and the corresponding grid frequency will also increase. rise.
  • the first controller can regularly obtain the first voltage and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first drive signal;
  • the first drive signal is adjusted to increase the frequency of the alternating current output by the inverter, and the photovoltaic power generation system
  • the output active power increases.
  • the active power output by the photovoltaic power generation system is less than or equal to the fifth set value, and the grid frequency is less than or equal to the maximum frequency value during normal operation of the grid.
  • the fifth setting value is the maximum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the first controller can regularly obtain the first voltage and the active power output by the inverter in the process of controlling the operating state of the inverter according to the first drive signal;
  • the first drive signal is adjusted so that the frequency of the alternating current output by the inverter decreases, And the active power output by the photovoltaic power generation system is reduced.
  • the active power output by the photovoltaic power generation system is greater than or equal to the sixth set value, and the grid frequency is greater than or equal to the minimum frequency value during normal operation of the grid.
  • the sixth setting value is the minimum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the first setting value and the fifth setting value in the above three embodiments may be the same.
  • the numerical values, the second set value, the third set value, the fourth set value and the sixth set value may be the same value.
  • the above formula 1 can be used to control the active power output by the inverter alone, or the above formula 2 and formula 3 can be used to control the DC voltage and frequency to achieve composite control.
  • the inverter 22 is connected to the DC converter 21.
  • the active power output by the inverter 22 is mainly obtained from the DC converter 21.
  • the inverter 22 can quickly output
  • the active power of the photovoltaic power generation system 20 provided by the embodiment of the present application may also include a second controller.
  • the second controller 25 may be connected to the DC converter 21 and may be connected to the third reference voltage according to the third reference voltage.
  • the third voltage difference between the two voltages generates a second driving signal, and the active power output by the DC converter 21 is controlled according to the second driving signal.
  • the third reference voltage is the rated voltage output by the DC converter 21 when the power grid is operating normally.
  • the second controller 25 can determine the frequency of the current power grid by detecting the DC bus voltage, thereby outputting active power for frequency support to the inverter 22 .
  • the second controller 25 can directly adjust the active power by detecting the current DC bus voltage through the corresponding relationship between the grid frequency and the DC bus voltage, thereby eliminating the need to use high-speed transmission lines to obtain the frequency situation on the grid side, and can solve the problem of DC conversion.
  • the frequency support of the device 21 is limited by frequency sampling performance and high-speed communication performance.
  • the DC converter 21 can control the power generation status of the inverter photovoltaic power generation system by controlling the DC bus voltage, so that the inverter can control the amount of active power output to the grid according to the power generation status, and inform the power grid frequency conversion Other equipment connected to the power grid.
  • the second controller is specifically used to: determine the working mode of the DC converter, which includes a one-way support mode and a two-way support mode; and generate a third reference according to the working mode of the DC converter and the operating parameters of the DC converter.
  • Voltage, the operating parameters of the DC converter include one or more of input current, input voltage and input power; according to the third voltage difference and the seventh droop coefficient, the fourth power value is obtained, and the seventh droop coefficient is based on the DC conversion
  • the corresponding relationship between the output voltage of the converter and the active power output by the DC converter is determined; according to the fourth power value and the maximum power value MPPE, the second active power control signal is determined; according to the second active power control signal and the DC converter input parameters to generate the second driving signal.
  • the second controller may further include a DC detection unit for detecting the DC bus voltage, obtaining the first voltage, and outputting the first voltage to the second droop calculation unit.
  • the second controller 25 is connected to the DC sensor, the signal input end of the DC sensor is connected to the output end of the DC converter, the signal output end of the DC sensor is connected to the second controller 25 , and the second controller 25 Pass Obtain the first voltage through the DC sensor.
  • the second droop calculation unit After receiving the first voltage and the reference voltage generated by the mode selection unit, the second droop calculation unit uses the following formula to calculate the second active power control signal used to achieve frequency support:
  • P BST is the generated second active power control signal
  • P MPPE is the estimated maximum power value
  • D PV is the seventh droop coefficient.
  • the seventh droop coefficient D PV may be, but is not limited to, a constant, an exponent and a power exponent.
  • the second controller 25 may determine the third reference voltage using the following formula
  • U BstBusRef is the set value
  • dU(P, U bus , ⁇ P) is the dynamic voltage adjustment value
  • P is the maximum power value output by the inverter
  • ⁇ P is the set additional reserved power value.
  • the dynamic voltage adjustment value can be obtained through a proportional controller, an integrator or other combinations.
  • the DC converter 24 connected to the photovoltaic module 24 dynamically adjusts its voltage value. Work in MPPT mode.
  • ⁇ P is zero.
  • ⁇ P can be 10% of the maximum power value, and other values can also be selected, for example, 15% of the maximum power value. %.
  • the purpose of setting ⁇ P is to control the DC converter to operate at reduced power and achieve two-way support for the grid frequency.
  • the bus reference voltage of the DC converter is mainly determined by the dynamic voltage point, that is, the DC converter 21 has a single unit with rapid power reduction.
  • the DC converter can operate in MPPT mode to ensure the power generation of the photovoltaic power generation system.
  • the DC converter 21 achieves the maximum power Pmppt1 output at the O1 operating point and has the ability to quickly support one-way power.
  • the MPPT unit will move the dynamic point of the DC converter 21 upward to the maximum power point O2, that is, mode selection.
  • the module updates the reference value of DC voltage droop.
  • the DC converter is realized to work in MPPT mode and has the ability to quickly support one-way power.
  • the operating voltage of the DC converter will drop to the maximum power point O3, realizing MPPT mode operation and having the ability to quickly support one-way power.
  • the bus reference voltage of the DC converter is not only determined by the dynamic point, but also uses ⁇ P to reduce the additional reserved power value, thereby making the DC
  • the reference voltage of the bus bar drops, allowing the DC converter to work in the power reserve mode, that is, during normal operation, the DC converter reduces the power output. Therefore, when the grid frequency drops or rises, its output power can be quickly increased or reduced, achieving two-way support capability.
  • the correspondence between the active power output by the DC converter and the DC bus voltage The relationship can be seen in Figure 10.
  • the selection of the working mode of the DC converter can be set according to the user's choice, or it can be set by receiving the selection instruction issued by the upper layer.
  • the DC converter is set with a default working mode.
  • the default working mode can be used to control the operation of the DC converter.
  • this application is applicable to the grid-connected architecture of other new energy systems, such as wind power generation systems and hydropower generation systems.
  • the above-mentioned new energy systems are all equipped with grid-connected inverters to combine the generated electric energy. It is also suitable for large-scale energy storage application scenarios, small and medium-sized distributed energy storage application scenarios, etc. This is only an example, and this application does not limit specific application scenarios.
  • this application is also applicable to off-grid scenarios of new energy systems.
  • embodiments of the present application also provide a control method for the photovoltaic power generation system, which is applied in the photovoltaic power generation system.
  • the method can be executed by a controller in the photovoltaic power generation system.
  • the controller in the photovoltaic power generation system includes a first controller connected to the inverter.
  • the method provided by the embodiment of this application specifically includes the following steps:
  • Step 1301 Monitor the operating parameters of the power grid, the first voltage of the DC power output by the DC converter, and the active power output by the inverter.
  • the first voltage is the voltage amplitude of the DC power output by the DC converter
  • the operating parameters of the power grid include one or more of reactive current, active current, reactive power, active power, voltage amplitude and power grid frequency.
  • corresponding AC sensors or DC sensors can be used to obtain the operating parameters of the power grid, the first voltage and the active power output by the inverter, such as voltage sensors and current sensors.
  • Step 1302 Generate a first driving signal according to two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, and control the operating state of the inverter according to the first driving signal.
  • the first driving signal is generated according to two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: according to the first voltage difference and the first frequency difference. value to generate a first active power control signal, where the first voltage difference is the difference between the first voltage and the first reference voltage, and the first frequency difference is the difference between the grid frequency and the first reference frequency.
  • the first reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally
  • the first reference frequency is the rated frequency value when the power grid is operating normally
  • the first drive is generated Signal.
  • generating the first driving signal according to the first active power control signal and the operating parameters of the power grid includes: generating the first modulated wave signal according to the first active power control signal and the operating parameters of the power grid; The first modulated wave signal and the first carrier wave signal generate a first driving signal, wherein the first carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating the first active power control signal according to the first voltage difference and the first frequency difference includes: using the first voltage difference and the first droop coefficient to obtain the first power value; The first droop coefficient is determined based on the corresponding relationship between the DC voltage output by the DC converter and the active power output by the DC converter; the second power value is obtained by using the first frequency difference and the second droop coefficient; the second droop coefficient is Determined according to the correspondence between the grid frequency and the active power output by the inverter; a first active power control signal is generated according to the first power value, the second power value and the third power value, where the third power value is The initial value of active power issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the above control method further includes: controlling the operation of the inverter according to the first driving signal.
  • the power grid frequency and the first voltage are obtained; when it is determined that the power grid frequency obtained this time is the same as that obtained in the adjacent time, and the first voltage obtained this time is greater than the first voltage obtained last time, the first driving signal is adjusted , so that the active power output by the photovoltaic power generation system is increased, wherein the active power output by the photovoltaic power generation system after adjusting the first driving signal is less than or equal to the first set value, and the first set value is the normal operation of the photovoltaic power generation system of the power grid.
  • the maximum active power output is the maximum active power output.
  • the above control method also includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the grid frequency and the first voltage; When the first voltage is the same and the grid frequency obtained this time is greater than the grid frequency obtained last time, the first driving signal is adjusted to reduce the active power output of the photovoltaic power generation system. After adjusting the first driving signal, the photovoltaic power generation The active power output by the system is greater than or equal to the second set value, and the second set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first driving signal is generated based on two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: based on the first power difference and the second frequency difference. value to generate a first voltage control signal, where the first power difference is the difference between the active power output by the inverter and the first reference power, and the second frequency difference is the difference between the grid frequency and the second reference frequency. The difference between first drive signal.
  • generating the first driving signal according to the first voltage control signal and the operating parameters of the power grid includes: generating a second modulated wave signal according to the first voltage control signal and the operating parameters of the power grid; The modulated wave signal and the second carrier wave signal generate a first drive signal, wherein the second carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating the first voltage control signal according to the first power difference and the second frequency difference includes: using the first power difference and the third droop coefficient to obtain the first DC voltage value; The three droop coefficients are determined based on the corresponding relationship between the active power output by the DC converter and the DC power output by the DC converter; the second DC voltage value is obtained by using the second frequency difference and the fourth droop coefficient; the fourth droop coefficient is Determined according to the corresponding relationship between the grid frequency and the DC output by the DC converter; generating a first voltage control signal according to the first DC voltage value, the second DC voltage value and the third DC voltage value, where the third DC voltage The value is the initial value of DC voltage issued by the power station management system, which is used to control the operating status of the photovoltaic power generation system.
  • the above control method also includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the grid frequency and the active power output by the inverter; When the active power output by the inverter obtained next time is the same and the grid frequency obtained this time is greater than the grid frequency obtained previously, the first drive signal is adjusted to increase the first voltage output by the DC converter, and the photovoltaic The active power output by the power generation system is reduced.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the third set value, and the third set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the above control method also includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the grid frequency and the active power output by the inverter;
  • the first driving signal is adjusted so that the first voltage of the DC converter output The voltage increases, and the active power output by the photovoltaic power generation system decreases.
  • the active power output by the photovoltaic power generation system after adjusting the first driving signal is greater than or equal to the fourth set value, and the fourth set value is the minimum active power output by the photovoltaic power generation system when the power grid is operating normally.
  • the first driving signal is generated according to two of the first voltage, the active power output by the inverter, and the operating parameters of the power grid, including: according to the second power difference and the second voltage difference. value, generate the first frequency rate control signal, wherein the second power difference is the difference between the active power output by the inverter and the second reference power, and the second voltage difference is the difference between the first voltage and the second reference voltage,
  • the second reference power is the rated active power value output by the inverter when the power grid is operating normally
  • the second reference voltage is the rated voltage value output by the DC converter when the power grid is operating normally; according to the first frequency control signal and the operating parameters of the power grid, a first drive signal.
  • generating the first driving signal according to the first frequency control signal and the operating parameters of the power grid includes: generating a third modulated wave signal according to the first frequency control signal and the operating parameters of the power grid; The modulated wave signal and the third carrier wave signal generate a first driving signal, wherein the third carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • generating the first frequency control signal according to the second power difference and the second voltage difference includes: using the second power difference and the fifth droop coefficient to generate the first frequency value, The fifth droop coefficient is determined based on the corresponding relationship between the active power output by the inverter and the grid frequency; the second voltage difference and the sixth droop coefficient are used to generate the second frequency value.
  • the sixth droop coefficient is based on the DC converter The corresponding relationship between the output DC power and the grid frequency is determined; the first frequency control signal is generated according to the first frequency value, the second frequency value and the third frequency value, where the third frequency value is issued by the power station management system.
  • the initial frequency value is used by the power station management system to control the operating status of the photovoltaic power generation system.
  • the above control method further includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the first voltage and the active power output by the inverter;
  • the first drive signal is adjusted to increase the frequency of the alternating current output by the inverter.
  • the active power output of the photovoltaic power generation system increases.
  • the active power output by the photovoltaic power generation system is less than or equal to the fifth set value, and the grid frequency is less than or equal to the maximum frequency value during normal operation of the grid.
  • the fifth setting value is the maximum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the above control method further includes: in the process of controlling the operating state of the inverter according to the first driving signal, obtaining the first voltage and the active power output by the inverter; When the first voltages obtained in adjacent times are the same and the active power output by the inverter obtained this time is greater than the active power output by the inverter obtained last time, the first driving signal is adjusted so that the AC power output by the inverter The frequency decreases, and the active power output by the photovoltaic power generation system decreases.
  • the active power output by the photovoltaic power generation system is greater than or equal to the sixth set value, and the grid frequency is greater than or equal to the minimum frequency value during normal operation of the grid.
  • the sixth setting value is the minimum active power output by the photovoltaic power generation system during normal operation of the power grid.
  • the method further includes: generating a second driving signal according to the first voltage and the third voltage difference, and controlling the active power output by the DC converter according to the second driving signal, wherein the third The voltage difference is the difference between the third reference voltage and the first voltage, and the third reference voltage is the rated voltage output by the DC converter when the power grid is operating normally.
  • generating the second driving signal according to the difference between the first voltage and the third voltage includes: determining the working mode of the DC converter, the working mode includes a one-way support mode and a two-way support mode; according to the DC converter
  • the operating mode of the converter and the operating parameters of the DC converter generate a third reference voltage.
  • the operating parameters of the DC converter include one or more of input current and input power; according to the third voltage difference and the seventh droop coefficient, we obtain The fourth power value and the seventh droop coefficient are determined based on the corresponding relationship between the output voltage of the DC converter and the active power output by the DC converter; the second active power control is determined based on the fourth power value and the maximum power value MPPE. signal; generating a second driving signal according to the second active power control signal and the input parameters of the DC converter.
  • generating the second driving signal according to the second active power control signal and the input parameters of the DC converter includes: generating a fourth driving signal according to the second active power control signal and the input parameters of the DC converter. Modulated wave signal; generate a second driving signal according to the fourth modulated wave signal and the fourth carrier wave signal, where the fourth carrier wave signal is a sine wave signal or a pulse signal with a fixed period.
  • the method further includes: determining the MPPE according to the operating parameters of the DC converter.
  • generating the third reference voltage according to the working mode of the DC converter and the operating parameters of the DC converter includes: determining the additional reserved power value according to the working mode of the DC converter; The operating parameters and additional reserved power value are used to generate the third reference voltage.
  • FIG. 14 a schematic flow chart of the first controller generating the first driving signal according to the first voltage and grid frequency is shown. Referring to Figure 14, the first controller performs the following steps:
  • Step 1401 Monitor the operating parameters and first voltage of the power grid.
  • the operating parameters of the power grid may include one or more of active power, reactive power, active current, reactive current, grid voltage and grid frequency.
  • Step 1402 Calculate the first voltage difference between the first voltage and the first reference voltage, and the first frequency difference between the grid frequency and the first reference frequency.
  • Step 1403 Generate a first active power control signal using the first voltage difference and the first frequency difference.
  • Step 1404 Generate a first driving signal according to the first active power control signal and the operating parameters of the power grid.
  • Step 1405 Output the first driving signal to the inverter.
  • FIG 15 it is a schematic flow chart for the first controller to generate the first driving signal according to the active power output by the inverter and the grid frequency. Referring to Figure 15, the first controller performs the following steps:
  • Step 1501 Monitor the operating parameters of the power grid and the active power output by the inverter.
  • the operating parameters of the power grid may include one or more of active power, reactive power, active current, reactive current, grid voltage and grid frequency.
  • Step 1502 Calculate the first power difference between the active power output by the inverter and the first reference power, and the second frequency difference between the grid frequency and the second reference frequency.
  • Step 1503 Generate a first voltage control signal using the first power difference and the second frequency difference.
  • Step 1504 Generate a first driving signal according to the first voltage control signal and the operating parameters of the power grid.
  • Step 1505 Output the first driving signal to the inverter.
  • FIG 16 it is a schematic flow chart of the first controller generating a first driving signal according to the active power output by the inverter and the first voltage output by the DC converter. Referring to Figure 16, the first controller performs the following steps :
  • Step 1601 Monitor the first voltage output by the DC converter and the active power output by the inverter.
  • Step 1602 Calculate the second voltage difference between the first voltage and the second reference voltage, and the second power difference between the active power output by the inverter and the second reference power.
  • Step 1603 Generate a first frequency control signal using the second power difference and the second voltage difference.
  • Step 1604 Generate a first driving signal according to the first frequency control signal and the operating parameters of the power grid.
  • Step 1605 Output the first driving signal to the inverter.
  • the active power output by the inverter is provided by the DC converter.
  • the DC side also needs to control the output power.
  • the inverter controller is based on the second voltage between the reference voltage and the DC bus voltage. The voltage difference is used to generate a second driving signal, and the active power output by the DC converter is controlled according to the second driving signal.
  • the inverter controller can obtain the fourth power value based on the second voltage difference and the third droop coefficient.
  • the third droop coefficient is based on the correspondence between the output voltage of the DC converter and the active power output by the DC converter. The relationship is determined; according to the fourth power value and the maximum power value, the second active power value is determined; according to the second active power control signal and the input parameters of the DC converter to generate a second driving signal.
  • controller in the photovoltaic power generation system also includes a second controller connected to the DC converter.
  • the method provided by the embodiment of the present application also includes the following steps:
  • Step 1701 Monitor the first voltage.
  • Step 1702 Determine the reference voltage according to the working mode of the DC converter.
  • Step 1703 Calculate the third voltage difference between the third reference voltage and the first voltage.
  • Step 1704 Generate a second active power control signal using the third voltage difference value and the maximum power value.
  • Step 1705 Generate a second driving signal according to the second active power control signal and the input parameters of the DC converter.
  • Step 1706 Send the second driving signal to the DC converter.
  • a computer program product includes one or more computer instructions.
  • Computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, e.g., computer instructions may be transmitted from a website, computer, server or data center via a wired link (e.g.
  • Coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless means to transmit to another website, computer, server or data center.
  • Computer-readable storage media can be any available media that can be accessed by a computer or a data storage device such as a server, data center, or other integrated media that includes one or more available media. Available media may be magnetic media (such as floppy disks, hard disks, magnetic tapes), or semiconductor media (such as solid state disks (SSD)), etc.
  • Embodiments of the present application also provide a readable storage medium for storing the method or algorithm provided in the above embodiments.
  • a readable storage medium for storing the method or algorithm provided in the above embodiments.
  • random access memory random access memory
  • RAM random access memory
  • flash memory read only memory
  • ROM read only memory
  • EPROM EPROM
  • register hard disk
  • removable memory Removable disk or any other form of storage media in this field.
  • the steps of the methods or algorithms described in the embodiments of the present application can be directly embedded in the control device.
  • the control device may include RAM memory, flash memory, ROM memory, EPROM memory, registers, hard disks, removable disks, or any other form of storage media in the field for storing steps of the methods or algorithms provided by the embodiments of the present application.
  • the storage medium can be connected to the processing module or processor (or controller) in the control device, so that the processing module, processor (or controller) can read information from the storage medium, and can send information to the storage medium. Save and write information.
  • the storage medium can also be integrated into the processing module, processor (or controller).
  • These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device.
  • Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

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Abstract

一种光伏发电系统和光伏发电系统的控制方法，用于实现快速频率支撑。该光伏发电系统包括：直流转换器，用于连接光伏组件的输出并将光伏组件输出的直流电进行电压转换；逆变器，用于将直流转换器输出的直流电转换为交流电并输出给电网；第一控制器，用于根据直流转换器的直流电的第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，并根据第一驱动信号控制逆变器的运行状态。

Description

一种光伏发电系统和光伏发电系统的控制方法
相关申请的交叉引用
本申请要求在2022年08月24日提交中国专利局、申请号为202211024308.0、申请名称为“一种光伏发电系统和光伏发电系统的控制方法”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
本申请涉及光伏领域，尤其涉及一种光伏发电系统和光伏发电系统的控制方法。
背景技术
随着构建以新能源为主体的新型电力系统的国家能源安全新战略逐步推进，风电、光伏等新能源发电系统在电网的角色将逐步从支撑电源转变为主力电源，因此，对新能源设备提出了更高的要求。随着光伏装机容量在电网的渗透率快速提升，光伏设备对电网的支撑能力将成为电力系统安全稳定的重要组成部分。然而，当前光伏建设项目中，光伏设备一般不具备电网频率和电压主动支撑能力，从而在一些高渗透率、大规模光伏通过长输电线路远距离外送的场景中，容易造成系统不稳定的问题。同时，当电网发生低频或过频率事件，新能源电力系统可能脱网。
发明内容
本申请提供一种光伏发电系统和光伏发电系统的控制方法，可以实现快速频率支撑。
第一方面，本申请实施例提供一种光伏发电系统，包括直流转换器、逆变器和逆变控制器。
其中，直流转换器用于连接光伏组件的输出将光伏组件输出的直流电进行电压转换；逆变器用于将直流转换器输出的直流电转换为交流电并输出给电网；第一控制器用于根据直流转换器输出的直流电的第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，并根据第一驱动信号控制逆变器的运行状态。其中，第一电压为直流转换器输出的直流电的电压幅值，电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一个或多个。
本申请实施例提供的光伏发电系统，当电网频率发生变化时，第一电压的幅值会发生变化，以及逆变器输出的有功功率也会造成电网频率的变化，即上述三个参数互相影响，因此，当第一控制器当检测到电网偏离其正常工作时的额定频率，可以利用上述三个参数中的任意两个生成相应的驱动信号并调整逆变器的运行状态，从而使逆变器输出的交流电可以实现频率支撑功能。
在一种可能的设计中，第一控制器具体用于：根据第一电压差值和第一频率差值，生成第一有功功率控制信号；根据第一有功功率控制信号和电网的运行参数，生成第一驱动信号。其中，第一电压为直流转换器输出的直流电的电压幅值，电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一个或多个。
采用上述光伏发电系统，可以根据第一电压和第一参考电压之间的第一电压差值执行逆变器输出的有功功率与直流电压之间的下垂控制，以及根据频率差值执行逆变器输出的有功功率与电网频率之间的下垂控制，并利用上述两个下垂控制策略共同决定用于实现频率支撑的有功功率值。
在一种可能的设计中，第一控制器具体用于：根据第一有功功率控制信号和电网的运行参数生成第一调制波信号；根据第一调制波信号与第一载波信号，生成第一驱动信号，其中，第一载波信号为周期固定的正弦波信号或者脉冲信号。
采用上述光伏发电系统，通过用于控制逆变器输出功率的第一调制波信号对第一载波信号进行调整，得到用于控制逆变器中开关管的导通时序的第一驱动信号，从而调整逆变器输出的有功功率值。
在一种可能的设计中，第一控制器具体用于：利用第一电压差值与第一下垂系数得到第一功率值；第一下垂系数是根据直流转换器输出的直流电和逆变器输出的有功功率之间的对应关系确定；利用第一频率差值与第二下垂系数得到第二功率值；第二下垂系数是根据电网频率与逆变器输出的有功功率之间的对应关系确定的；根据第一功率值、第二功率值和第三功率值，生成第一有功功率控制信号。其中，第三功率值为电站管理系统下发的有功功率初始值，电站管理系统用于控制光伏发电系统的运行状态。
采用上述光伏发电系统，电网频率与逆变器输出的有功功率之间的对应关系以及直流转换器输出的直流电压与逆变器输出的有功功率之间的对应关系选择合适的下垂曲线，从而改善频率支撑效果。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，第一设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
采用上述光伏发电系统，当电网频率不变、且直流转换器输出的第一电压上升时，则直流转换器输出给逆变器的有功功率增大，在不影响电网运行的情况下，可以控制光伏发电系统输出的有功功率上升。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，第二设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
采用上述光伏发电系统，当电网频率上升时，即表明光伏发电系统输出的有功功率上升，相应的，当电网频率下降，则光伏发电系统输出的有功功率下降，为了不影响电网的运行，当电网频率上升时，可以控制光伏发电系统输出的有功功率下降。
在一种可能的设计中，第一控制器具体用于：根据第一功率差值和第二频率差值，生成第一电压控制信号；根据第一电压控制信号和电网的运行参数，生成第一驱动信号。其中，第一功率差值为逆变器输出的有功功率与第一参考功率之间的差值，第二频率差值为电网频率与第二参考频率之间的差值，第一参考功率为电网正常运行时逆变器输出的额定有功功率值，第一参考频率为电网正常运行时的额定频率值。
采用上述光伏发电系统，可以根据第一功率差值执行逆变器输出的有功功率与直流侧电压之间的下垂控制，以及根据第二频率差值执行电网频率与直流侧电压之间的下垂控制，并利用上述两个下垂控制策略共同决定用于控制逆变器驱动信号的直流电压幅值，并通过控制逆变器的驱动信号，实现频率快速支撑。
在一种可能的设计中，第一控制器具体用于：根据第一电压控制信号和电网的运行参数生成第二调制波信号；根据第二调制波信号与第二载波信号，生成第一驱动信号，其中，第二载波信号为周期固定的正弦波信号或者脉冲信号。
采用上述光伏发电系统，通过用于控制逆变器输出功率的第二调制波信号对第二载波信号进行调整，得到用于控制逆变器中开关管的导通时序的第一驱动信号，从而调整逆变器的输出参数。
在一种可能的设计中，第一控制器具体用于利用第一功率差值与第三下垂系数得到第一直流电压值；第三下垂系数是根据直流转换器输出的有功功率与直流转换器输出的直流电之间的对应关系确定的；利用第二频率差值与第四下垂系数得到第二直流电压值；第四下垂系数是根据电网频率与直流转换器输出的直流电之间的对应关系确定的；根据第一直流电压值、第二直流电压值和第三直流电压值，生成第一电压控制信号，其中，第三直流电压值为电站管理系统下发的直流电压初始值，电站管理系统用于控制光伏发电系统的运行状态。
采用上述光伏发电系统，电网频率与直流转换器输出的第一电压之间的对应关系以及逆变器输出的有功功率与直流转换器输出的第一电压之间的对应关系选择合适的下垂曲线，从而改善频率支撑效果。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，第三设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
采用上述光伏发电系统，当电网频率上升时，即表明光伏发电系统输出的有功功率超出电网对电能需求，为了不影响电网的运行，当电网频率上升时，可以控制光伏发电系统输出的有功功率下降。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，第四设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
采用上述光伏发电系统，为了避免光伏发电系统输出的有功功率上升超出电网对电能的需求，当检测到光伏发电系统输出有功功率上升时，可以通过调整第一驱动信号，控制光伏发电系统输出的有功功率下降，来实现电网的平稳运行。
在一种可能的设计中，第一控制器具体用于：根据第二功率差值和第二电压差值，生成第一频率控制信号；根据第一频率控制信号和电网的运行参数，生成第一驱动信号。其 中，第二功率差值为逆变器输出的有功功率与第二参考功率之间的差值，第二电压差值为第一电压与第二参考电压之间的差值，第二参考功率为电网正常运行时逆变器输出的额定有功功率值，第二参考电压为电网正常运行时直流转换器输出的额定电压值。
采用上述光伏发电系统，可以根据第二功率差值执行电网频率与逆变器输出的有功功率之间的下垂控制，以及根据第二电压差值执行电网频率与直流转换器输出的第一电压之间的下垂控制，并利用上述两个下垂控制策略共同决定逆变器输出的频率，并通过调整逆变器输出的频率实现频率支撑效果。
在一种可能的设计中，第一控制器具体用于：根据第一频率控制信号和电网的运行参数生成第三调制波信号；根据第三调制波信号与第三载波信号，生成第一驱动信号，其中，第三载波信号为周期固定的正弦波信号或者脉冲信号。
采用上述光伏发电系统，通过用于控制逆变器输出功率的第三调制波信号对第三载波信号进行调整，得到用于控制逆变器中开关管的导通时序的第一驱动信号，从而调整逆变器的输出参数。
在一种可能的设计中，第一控制器具体用于：利用第二功率差值与第五下垂系数，生成第一频率值，第五下垂系数是根据逆变器输出的有功功率与电网频率之间的对应关系确定的；利用第二电压差值与第六下垂系数，生成第二频率值，第六下垂系数是根据直流转换器输出的直流电与电网频率之间的对应关系确定的；根据第一频率值、第二频率值和第三频率值，生成第一频率控制信号。其中，第三频率值为电站管理系统下发的初始频率值，电站管理系统用于控制光伏发电系统的运行状态。
采用上述光伏发电系统，电网频率与逆变器输出的有功功率之间的对应关系以及直流转换器输出的第一电压与电网频率之间的对应关系选择合适的下垂曲线，从而改善频率支撑效果。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使逆变器输出的交流电的频率上升，以及光伏发电系统输出的有功功率增大。其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及所述电网频率小于或等于电网正常运行时的频率最大值，第五设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
采用上述光伏发电系统，当直流转换器输出的第一电压上升时，则直流转换器输出给逆变器的有功功率增大，在不影响电网运行的情况下，可以控制光伏发电系统输出的有功功率上升。
在一种可能的设计中，第一控制器还用于：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使逆变器输出的交流电的频率下降，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，以及所述电网频率大于或等于电网正常运行时的频率最小值，第六设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的设计中，光伏发电系统还包括与直流转换器连接的第二控制器，用于根 据第三电压差值，生成第二驱动信号，并根据第二驱动信号控制直流转换器输出的有功功率。其中，第三电压差值为第三参考电压与第一电压之间的差值，第三参考电压为电网正常运行时直流转换器输出的额定电压。
采用上述光伏发电系统，由于逆变器与直流转换器连接，即逆变器输出的有功功率主要由直流转换器提供，为了实现逆变器可以输出用于实现频率支撑的有功功率，可以通过直流控制器调整直流转换器输出的有功功率，从而使输出的有功功率满足频率支撑的需求。另外，由于第二控制器可以直接通过第一电压确定电网频率情况，从而无需通过高速传输线获取电网频率，加快了光伏发电系统的频率支撑速度。
在一种可能的设计中，第二控制器具体用于：确定直流转换器的工作模式，工作模式包括单向支撑模式和双向支撑模式；根据直流转换器的工作模式和直流转换器运行参数生成第三参考电压，直流转换器的运行参数包括输入电流、输入电压和输入功率中的一个或多个；根据第三电压差值和第七下垂系数，得到第四功率值，第七下垂系数是根据直流转换器的输出电压和直流转换器输出的有功功率之间的对应关系确定的；根据第四功率值和最大功率值，确定第二有功功率控制信号；根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号。
采用上述光伏发电系统，当电网频率上升时，则直流转换器的输出电压上升，相应的，当电网频率下降，则直流转换器的输出电压下降，因此可以通过直流转换器输出的电压与参考电压之间的第二电压差值，确定当前电网情况，并进行相应的功率调整，实现频率支撑。
在一种可能的设计中，第二控制器还用于根据直流转换器的运行参数，计算最大功率值MPPE。
采用上述光伏发电系统，直流转换器在无频率支撑的情况下会运行在MPPT模式下，并输出最大功率值，当需要进行电网频率支撑时，可以利用MPPE进行最大功率值的估算，并在最大功率值的基础上进行功率调整。
在一种可能的设计中，第二控制器具体用于：根据直流转换器的工作模式确定附加预留功率值；根据直流转换器的运行参数和附加预留功率值，生成第三参考电压。
采用上述光伏发电系统，可以根据直流转换器的运行参数和设定的附加预留功率值确定直流转换器的输出功率情况，从而动态调整参考电压值。
第二方面，本申请实施例提供一种光伏发电系统的控制方法，该方法可以应用于光伏发电系统中，其具体包括以下步骤：监控电网的运行参数、逆变器输出的第一电压和直流转换器输出的有功功率；根据第一电压、直流转换器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，并根据第一驱动信号控制逆变器的运行状态，其中，第一电压为直流转换器输出的直流电的电压幅值，电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一个或多个。
在一种可能的设计中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第一电压差值和第一频率差值，生成第一有功功率控制信号，其中，第一电压差值为第一电压与第一参考电压之间的差值，第一频率差值为电网频率与第一参考频率之间的差值，第一参考电压为电网正常运行时直流转换器输出的额定电压值，第一参考频率为电网正常运行时的额定频率值；根据第一有功功率控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的设计中，根据第一有功功率控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一有功功率控制信号和电网的运行参数生成第一调制波信号；根据第一调制波信号与第一载波信号，生成第一驱动信号，其中，第一载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的设计中，根据第一电压差值和第一频率差值，生成第一有功功率控制信号，包括：利用第一电压差值与第一下垂系数得到第一功率值；第一下垂系数是根据直流转换器的输出的直流电压和直流转换器输出的有功功率之间的对应关系确定；利用第一频率差值与第二下垂系数得到第二功率值；第二下垂系数是根据电网频率与逆变器输出的有功功率之间的对应关系确定的；根据第一功率值、第二功率值和第三功率值，生成第一有功功率控制信号，其中，第三功率值为电站管理系统下发的有功功率初始值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，第一设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，第二设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的设计中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第一功率差值和第二频率差值，生成第一电压控制信号，其中，第一功率差值为逆变器输出的有功功率与第一参考功率之间的差值，第二频率差值为电网频率与第二参考频率之间的差值，第一参考功率为电网正常运行时逆变器输出的额定有功功率值，第一参考频率为电网正常运行时的额定频率值；根据第一电压控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的设计中，根据第一电压控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一电压控制信号和电网的运行参数生成第二调制波信号；根据第二调制波信号与第二载波信号，生成第一驱动信号，其中，第二载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的设计中，根据第一功率差值和第二频率差值，生成第一电压控制信号，包括：利用第一功率差值与第三下垂系数得到第一直流电压值；第三下垂系数是根据直流转换器输出的有功功率与直流转换器输出的直流电之间的对应关系确定的；利用第二频率差值与第四下垂系数得到第二直流电压值；第四下垂系数是根据电网频率与直流转换器输出的直流电之间的对应关系确定的；根据第一直流电压值、第二直流电压值和第三直流电压值，生成第一电压控制信号，其中，第三直流电压值为电站管理系统下发的直流电压初始值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出 的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，第三设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，第四设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的设计中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第二功率差值和第二电压差值，生成第一频率控制信号，其中，第二功率差值为逆变器输出的有功功率与第二参考功率之间的差值，第二电压差值为第一电压与第二参考电压之间的差值，第二参考功率为电网正常运行时逆变器输出的额定有功功率值，第二参考电压为电网正常运行时直流转换器输出的额定电压值；根据第一频率控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的设计中，根据第一频率控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一频率控制信号和电网的运行参数生成第三调制波信号；根据第三调制波信号与第三载波信号，生成第一驱动信号，其中，第三载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的设计中，根据第二功率差值和第二电压差值，生成第一频率控制信号，包括：利用第二功率差值与第五下垂系数，生成第一频率值，第五下垂系数是根据逆变器输出的有功功率与电网频率之间的对应关系确定的；利用第二电压差值与第六下垂系数，生成第二频率值，第六下垂系数是根据直流转换器输出的直流电与电网频率之间的对应关系确定的；根据第一频率值、第二频率值和第三频率值，生成第一频率控制信号，其中，第三频率值为电站管理系统下发的初始频率值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使逆变器输出的交流电的频率上升，以及光伏发电系统输出的有功功率增大。其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及所述电网频率小于或等于电网正常运行时的频率最大值。第五设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
在一种可能的设计中，该方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使逆变器输出的交流电的频率下降，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，以及所述电网频率大于或等于电网正常运行时的频率最小值。第六设定值为电网正常运行 时光伏发电系统输出的有功功率最小值。
在一种可能的设计中，该方法还包括：根据第一电压和第三电压差值，生成第二驱动信号，并根据第二驱动信号控制直流转换器输出的有功功率，其中，第三电压差值为第三参考电压与第一电压之间的差值，第三参考电压为电网正常运行时直流转换器输出的额定电压。
在一种可能的设计中，根据第一电压和第三电压差值，生成第二驱动信号，包括：确定直流转换器的工作模式，工作模式包括单向支撑模式和双向支撑模式；根据直流转换器的工作模式和直流转换器的运行参数生成第三参考电压，直流转换器的运行参数包括输入电流和输入功率中的一个或多个；根据第三电压差值和第七下垂系数，得到第四功率值，第七下垂系数是根据直流转换器的输出电压和直流转换器输出的有功功率之间的对应关系确定的；根据第四功率值和最大功率值MPPE，确定第二有功功率控制信号；根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号。
在一种可能的设计中，根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号，包括：根据第二有功功率控制信号与直流转换器的输入参数，生成第四调制波信号；根据第四调制波信号与第四载波信号，生成第二驱动信号，其中，第四载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的设计中，该方法还包括：根据直流转换器的运行参数确定MPPE。
在一种可能的设计中，根据直流转换器的工作模式和直流转换器的运行参数生成第三参考电压，包括：根据直流转换器的工作模式确定附加预留功率值；根据直流转换器的运行参数和附加预留功率值，生成第三参考电压。
上述第二方面可以达到的技术效果可以参照上述第一方面中有益效果的描述，此处不再重复赘述。
附图说明
图1为本申请实施例提供的一种光伏发电系统的结构示意图一；
图2为本申请实施例提供的一种光伏发电系统的结构示意图二；
图3为本申请实施例提供的一种逆变器输出的有功功率与直流电压之间对应关系示意图；
图4为本申请实施例提供的一种逆变器输出的有功功率与电网频率之间的对应关系示意图；
图5为本申请实施例提供的一种直流电压与电网频率之间的对应关系示意图；
图6为本申请实施例提供的一种光伏发电系统的结构示意图三；
图7为本申请实施例提供的一种直流转换器输出的有功功率与直流电压之间的对应关系示意图一；
图8为本申请实施例提供的一种光伏发电系统的输出波形示意图一；
图9为本申请实施例提供的一种光伏发电系统的输出波形示意图二；
图10为本申请实施例提供的一种直流转换器输出的有功功率与直流电压之间的对应关系示意图二；
图11为本申请实施例提供的一种光伏发电系统的输出波形示意图三；
图12为本申请实施例提供的一种光伏发电系统的输出波形示意图四；
图13为本申请实施例提供的一种光伏发电系统的控制方法的流程示意图一；
图14为本申请实施例提供的一种光伏发电系统的控制方法的流程示意图二；
图15为本申请实施例提供的一种光伏发电系统的控制方法的流程示意图三；
图16为本申请实施例提供的一种光伏发电系统的控制方法的流程示意图四；
图17为本申请实施例提供的一种光伏发电系统的控制方法的流程示意图五。
具体实施方式
为了使本申请实施例的目的、技术方案和优点更加清楚，下面将结合附图，对本申请实施例进行详细描述。本申请的实施方式部分使用的术语仅用于对本申请的具体实施例进行解释，而非旨在限定本申请。显然，所描述的实施例仅仅是本申请一部分实施例，并不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应理解这样使用的数据在适当情况下可以互换，以便这里描述的本申请的实施例能够以除了在这里图示或描述的那些以外的顺序实施。以下示例性实施例中所描述的实施方式并不代表与本申请相一致的所有实施方式。相反，它们仅是与如所附权利要求书中所详述的、本申请的一些方面相一致的装置和方法的例子。
以下，对本申请实施例中的部分用语进行解释说明，以便于本领域技术人员理解。
(1)本申请实施例中术语“多个”是指两个或两个以上，其它量词与之类似。
(2)本申请实施例中的开关管可以是继电器、金属氧化物半导体场效应晶体管(metal oxide semiconductor field effect transistor，MOSFET)，双极结型管(bipolar junction transistor，BJT)，绝缘栅双极型晶体管(insulated gate bipolar transistor，IGBT)、碳化硅(SiC)晶体管等多种类型的开关管中的一种或多种，本申请实施例对此不再一一列举。各个开关管的封装形式可以是单管封装，也可以是多管封装，本申请实施例对此并不多作限制。每个开关管皆可以包括第一端、第二端和控制端，其中，控制端用于控制开关管的导通或断开。当开关管导通时，开关管的第一端和第二端之间可以传输电流，当开关管断开时，开关管的第一端和第二端之间无法传输电流。以为MOSFET例，开关管的控制端为栅极，开关管的第一端可以是源极，第二端可以是漏极，或者，第一端可以是漏极，第二端可以是源极。
(3)本申请实施例中“连接”可以理解为电连接，两个电学元件连接可以是两个电学元件之间的直接或间接连接。例如，A与B连接，既可以是A与B直接连接，也可以是A与B之间通过一个或多个其它电学元件间接连接，例如A与B连接，也可以是A与C直接连接，C与B直接连接，A与B之间通过C实现了连接。本申请实施例中的“连接”也可以理解为无线连接，即两个电学元件连接可以是两个电学元件电磁连接。
(4)有功-频率下垂控制，利用有功功率与电网的频率之间的近似线性关系，可以构建有功-频率下垂控制。通过有功-频率下垂控制可以在电网无法满足负载需求导致电网的频率发生波动时，可以控制逆变器输出用于控制电网的频率恢复正常的有功功率。
(5)电压-有功下垂控制，建立逆变器输入侧直流电压与逆变器输出的有功功率之间的近似线性关系，并利用该近似线性关系构建电压-有功下垂控制。通过电压-有功下垂控制可以在电网无法满足负载需求导致电网的频率发生波动时，可以控制逆变器输出用于控 制电网的频率恢复正常的有功功率。
(6)电压-频率下垂控制，建立直流电压与电网的频率之间的近似线性关系，并利用该近似线性关系构建电压-频率下垂控制。通过直流电压-频率下垂控制可以在电网无法满足负载需求导致电网的频率发生波动时，可以控制直流转换器输出满足电网频率恢复所需的有功功率。
(7)最大功率点跟踪(maximum power point tracking，MPPT)模式，直流转换器的控制器可以对光伏组件进行最大功率点跟踪，可以显著提高光伏阵列的输出功率，进而提高光伏系统的能量利用率。
(8)最大功率点估计(maximum power point estimation，MPPE)模式，直流转换器的控制器可以对光伏组件进行最大功率点估算。
本申请所公开的方案可以应用于新能源系统，并应用于新能源系统的并网场景中。其中，新能源系统可包括但不限于：光伏发电系统、风力发电系统、水利发电系统等。
在一种具体的应用场景中，上述新能源系统可以为光伏发电系统。图1示例性示出了一种光伏发电系统的结构示意图。参照图1所示，光伏发电系统主要包括直流转换器、逆变器和控制器。其中，光伏发电系统与光伏组件连接，并将光伏组件输出的电能输出给电网。
在一种可能的实现方式中，光伏发电系统包括光伏组件。
在光伏发电系统并网过程中，光伏组件可以将光能转换为直流电；直流转换器与光伏组件的输出端连接，可以接收光伏组件输出的直流电，并对接收的直流电进行电压转换；逆变器可以接收直流转换器输出的经过电压转换后的直流电，并将接收的直流电转换为交流电，并通过并网点输出给电网，从而实现光伏发电系统并网；控制器与逆变器连接，用于控制逆变器将接收的直流电转换为交流电。其中，直流转换器一般通过直流母线与逆变器连接，即直流转换器输出的直流电的电压幅值即为直流母线电压。
实际使用时，逆变器由多个开关器件组成，控制器通过向逆变器中的多个开关发送驱动信号，控制逆变器中多个开关器件的导通状态，从而控制逆变器的运行。
继续参见图1所示，控制器与光伏发电系统上层的电站管理系统连接，并在接收到电站管理系统发送的控制指令时，调整逆变器的运行状态。具体地，电站管理系统可以定期或实时获取电网的运行参数，对电网的运行状态进行监控，当电网故障或者连接的负载大幅变化导致电网的频率发生变换时，电站管理系统可以根据电网的运行情况，计算用于频率支撑所需的有功功率值，并向控制器下发调度指令，控制器接收到上述调度指令后通过调整逆变器中开关管的驱动信号，调整逆变器输出的有功功率值，从而实现电网的频率支撑功能。
实际使用时，控制器的频率支撑功能通过上层的电站管理系统下发的调度指令实现，控制器受电站管理系统协调控制，当电网的频率发生波动时，响应速度慢。
有鉴于此，本申请实施例提供一种光伏发电系统和光伏发电系统的控制方法，用于快速实现频率支撑。为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
图2为本申请实施例提供的一种光伏发电系统的结构示意图。参见图2所示，光伏发电系统20包括直流转换器21、逆变器22和第一控制器23。其中，直流转换器21的输入端与光伏组件24的输出端连接，直流转换器21的输出端与逆变器22连接；逆变器22与 第一控制器23连接。
在一示例中，光伏发电系统20中还可以包括光伏组件24。
参见图2所示，在光伏发电系统20并网过程中，光伏组件24可以将光能转换为直流电，并将该直流电输出给直流转换器21；直流转换器21可以将光伏组件24输出的直流电进行电压转换，并将电压转换后的直流电输出；逆变器22可以将直流转换器21输出的直流电转换为交流电并输出给电网，从而实现光伏发电系统并网；第一控制器23与逆变器22连接，可以控制逆变器22将接收的直流电转换为交流电。其中，直流转换器21与逆变器22之间通过直流母线连接。
实际使用时，直流转换器21通过直流母线与逆变器22连接，直流转换器21输出的交流电的电压即为直流母线电压。
具体地，第一控制器23可以根据直流转换器21输出的直流电的第一电压、逆变器22输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，并根据第一驱动信号控制逆变器22的运行状态，从而实现逆变器22输出的交流电可以实现频率支撑功能。
参见图2所示，光伏发电系统20在并网过程中，当电网频率发生变化时，第一电压的幅值会发生变化，以及逆变器22输出的有功功率也会造成电网频率的变化，即上述三个参数互相影响，因此，当第一控制器当检测到电网偏离其正常工作时的额定频率，可以利用上述三个参数中的任意两个参数生成另一个参数的调整值，并通过生成相应的驱动信号，使逆变器22输出用于实现频率支撑的交流电，实现光伏发电系统的频率支撑功能。
其中，电网的运行参数可以包括以下一个或多个：无功电流、有功电流、有功功率、无功功率、电压幅值和电网频率。
应理解，在本申请实施例提供的光伏发电系统20中，可以通过光伏发电系统20本地的第一控制器23进行频率支撑计算，相比于现有技术中上层的电站管理系统进行频率支撑计算，减小了电网频率以及相关参数的获取时间和调度指令的下发时间，从而可以实现快速频率支撑，使电网快速恢复至稳定状态。
另外，本申请实施例提供的光伏发电系统20，将表征光伏发电系统20产量情况的第一电压参与频率支撑计算，考虑了光伏发电系统20的产电情况，在不影响电网运行的情况下，可以适量增大光伏发电系统20输出的有功功率数值，从而加大电网中新能源的占比。
实际使用时，逆变器22可以由开关管、二极管、电感、电容等器件组成。逆变器22的工作状态可以通过调节这些器件(例如开关管)的工作状态来实现。
具体地，若逆变器22中的开关管为MOS管，第一控制器23可以与MOS管的栅极连接，从通过控制MOS管的通断来调整逆变器22的运行情况；若逆变器22中的开关管为BJT，第一控制器23可以与BJT的基极连接，从通过控制BJT的通断来调整逆变器22的运行情况。
下面结合实施例对第一控制器23采用不同参数实现频率支撑的过程进行说明。
实施例一
实际使用时，第一控制器23根据直流转换器21输出的第一电压和电网频率，生成第一驱动信号。
具体地，第一控制器23可以计算第一电压与第一参考电压之间的第一电压差值，计算电网频率与第一参考频率之间的第一频率差值；根据第一电压差值和第一频率差值，生 成第一有功功率控制信号；根据第一有功功率控制信号和电网当前运行参数，生成第一驱动信号。其中，第一参考电压电网正常运行时直流转换器21输出额定电压值。第一参考频率为电网正常运行时的额定频率值。
实际使用时，当电网频率高于第一参考频率时，则表征电网上当前传输的有功功率高于电网实际需求的有功功率。当电网的频率低于第一参考频率时，则表征电网上当前传输的有功功率低于电网实际需求的有功功率，根据上述电网频率与逆变器输出的有功功率的对应关系，建立有功-频率下垂控制策略。同理，当直流转换器21输出的第一电压高于第一参考电压时，则表明直流转换器21输出的功率超出电网正常运行时的额定功率值，当逆变器将上述功率发送给电网时，电网上传输的功率会超出电网实际需求的功率。当直流转换器21输出的第一电压低于第一参考功率时，则表明直流转换器21输出的功率超出电网正常运行时的额定功率，当逆变器将上述功率发送给电网时，电网上传输的功率会小于电网实际需求的功率，基于上述逆变器输出的有功功率与直流母线电压之间的对应关系，建立电压-有功下垂控制策略。通过上述两个下垂控制策略计算得到频率支撑所需的有功功率值。
实际使用时，第一控制器23利用第一电压差值与第一下垂系数构成电压-有功下垂控制策略，得到第一功率值；第一控制器23利用第一频率差值与第二下垂系数得到第二功率值，其中，第二下垂系数是根据电网频率与逆变器输出的有功功率之间的对应关系确定的；利用上述两个下垂控制策略得到的第一功率值、第二功率值和第三功率值生成频率支撑所需的第一有功功率控制信号。其中，第一下垂系数是根据直流转换器输出的直流电和逆变器输出的有功功率之间的对应关系确定的。同理，第三功率值为电站管理系统下发的有功功率初始值，电站管理系统用于控制光伏发电系统20的运行状态。
在一示例中，第一控制器23可以分别与直流传感器和交流传感器连接，直流传感器用于检测直流转换器21输出的第一电压，交流传感器可以检测电网的运行参数。其中，交流检测单元可以是但不限于电压传感器和电流传感器。例如，霍尔传感器。
实际使用时，当第一控制器23获取到上述传感器检测的数值之后，可以利用下述公式计算用于进行功率支撑的第一有功功率控制信号PINV：
其中，Kup第一下垂系数，Kpf为第二下垂系数，Ubus为第一电压，为第一参考电压，freq为电网的频率，为第一参考频率，Pcmd为上层的电站管理系统下发的有功功率初始值。其中，第一下垂系数Kup和第二下垂系数Kpf可以是但不限于常数、指数和幂指数。
具体实施时，第一下垂系数是根据直流母线电压与逆变器22输出的有功功率之间的对应关系曲线设置的，第二下垂系数是根据逆变器输出的有功功率与电网频率之间的对应关系曲线设置的。其中，上述数值可以通过比例控制器，积分器、其它组合或者用户选择配置。
参见图2所示，第一控制器23利用上述公式一生成第一有功功率控制信号，利用第一有功功率控制信号以及当前电网的运行参数生成第一调制波信号，该第一调制波信号与第一载波信号比较后生成第一驱动信号，并发送给逆变器22中的开关管，逆变器22中的开关管在上述第一驱动信号的控制下调整其导通时序，从而调整逆变器22输出的有功功率值，实现频率支撑功能。其中，第一载波信号可以是周期固定的正弦波信号或者脉冲信 号。
由上述公式一可知，可以利用直流母线电压的动态变化和电网频率的动态变化对逆变器22输出的有功功率进行动态调整。
具体地，第一控制器23利用电压-有功下垂控制策略和有功-频率下垂控制策略共同调整逆变器22输出的有功功率。参见公式一可知，当电网频率保持不变时，由于直流转换器21工作在MPPT模式下，随着直流母线电压在[Ubusmin，Ubusmax]范围内逐步增大，则说明光伏发电系统20的产电量逐渐增大时，在不影响电网运行的情况下，可以控制逆变器22输出的有功功率值单调上升，其逆变器22输出的有功功率与直流电压之间的对应关系可参见图3所示。其中，上述直流母线电压范围为直流转换器21正常工作时直流母线的运行范围，根据直流转换器21的运行电压和逆变器输出侧的交流电压幅值共同决定。
实际应用时，第一控制器可以在跟据第一驱动信号控制逆变器的运行状态的过程中，定期获取电网频率和第一电压；在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使光伏发电系统输出的有功功率增大。其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，第一设定值为电网正常运行时光伏发电系统输出的有功功率最大值。其中，第一设定值可以根据电网连接的电能设备进行配置。
在一示例中，当逆变器22输出的有功功率增大时，会使电网上的频率上升，电网上的其它设备可以减小传输给电网的电量，从而实现与电网上其它设备的协调控制。
具体地，第一控制器23利用电压-有功下垂控制策略和有功-频率下垂控制策略共同调整逆变器22输出的有功功率。参见公式一可知，当直流母线电压保持不变时，随着电网频率在[freqmin，freqmax]范围逐步增大，则说明当前电网上传输的有功功率逐渐越多、且超出电网实际需求的有功功率，可以控制逆变器22输出的有功功率单调下降，其中，逆变器22输出的有功功率与电网频率之间的对应关系可参见图4所示。其中，上述电网频率范围为电网正常工作时的波动范围。
实际应用时，第一控制器可以在跟据第一驱动信号控制逆变器的运行状态的过程中，定期获取电网频率和第一电压；在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，第二设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
结合图3和图4，以及公式一的内容可知，在逆变器22输出的有功功率固定的情况下，直流母线电压与电网频率之间的对应关系可参见图5所示。
实施例二
实际使用时，第一控制器23根据逆变器22输出的有功功率和电网频率，生成第一驱动信号。
具体地，第一控制器23可以根据第一功率差值和第二频率差值，生成第一电压控制信号，根据第一电压控制信号和电网的运行参数，生成第一驱动信号。其中，第一功率差值为逆变器22输出的有功功率与第一参考功率之间的差值，第二频率差值为电网频率与第二参考频率之间的差值，第一参考功率为电网正常运行时逆变器22输出的额定有功功率值，第一参考频率为电网正常运行时的额定频率值。
实际使用时，当电网频率高于第二参考频率时，则表征电网上当前传输的有功功率高 于电网实际需求的有功功率。当电网的频率低于第二参考频率时，则表征电网上当前传输的有功功率低于电网实际需求的有功功率，根据上述电网频率与有功功率的对应关系，建立有功-频率下垂控制策略。同理，当电网频率高于第二参考频率时，直流母线电压上升，当电网频率低于第一参考频率时，则直流母线电压下降，基于上述电网频率与直流母线电压之间的对应关系，建立电压-频率下垂控制策略。通过上述两个下垂控制策略计算用于频率支撑的第一电压。
具体地，第一控制器23利用第一功率差值与第三下垂系数得到第一直流电压值；第三下垂系数是根据直流转换器21输出的有功功率与直流转换器21输出的直流电之间的对应关系确定的；利用第二频率差值与第四下垂系数得到第二直流电压值；第四下垂系数是根据电网频率与直流转换器输出的直流电之间的对应关系确定的；根据第一直流电压值、第二直流电压值和第三直流电压值，生成第一电压控制信号。其中，第三直流电压值为电站管理系统下发的直流电压初始值，电站管理系统用于控制光伏发电系统的运行状态。
应理解，逆变器22可以工作在MPPT模式下，当逆变器22可以通过调整直流转换器的输出电压，控制直流转换器的输出功率，因此，当逆变器22的输入电压发生改变时，其输出给电网的电压也会发生改变，从而实现频率支撑。
在一示例中，第一控制器23可以分别与第一传感器和第二传感器连接，第一传感器用于检测电网的运行参数，第二传感器用于检测逆变器22输出的有功功率。其中，第一传感器和第二传感器均为交流传感器，例如，霍尔传感器。
具体地，第一控制器23利用电网频率的动态变化和逆变器22输出的有功功率的动态变化对逆变器侧的直流电压进行动态调整，具体地，第一控制器23采用以下公式计算用于频率支撑的第一电压控制信号：
其中，为生成的第一电压控制信号，为电站管理系统下发的直流电压初始值，Dup为第三下垂系数，Duf为第四下垂系数，PINVRef为功率指令值，PINV为逆变器输出有功功率。freq为电网的频率，为参考频率。
其中，第三下垂系数是根据直流转换器21输出的有功功率与直流转换器输出的直流电之间的对应关系确定的，第四下垂系数是根据电网频率与直流转换器21输出的直流电之间的对应关系确定的。
具体地，第三下垂系数是根据直流母线电压与逆变器22输出的有功功率之间的对应关系曲线设置的，第四下垂系数是根据直流转换器21输出的第一电压与电网频率之间的对应关系曲线设置的。其中，上述数值可以通过比例控制器，积分器、其它组合或者用户选择配置。
参见图2所示，第一控制器23利用上述公式二生成用于实现频率支撑的第一电压控制信号，利用第一电压控制信号以及当前电网的运行参数生成第二调制波信号，该第二调制波信号与第二载波信号比较后生成第一驱动信号，并发送给逆变器22中的开关管，逆变器22中的开关管在上述第二驱动信号的控制下调整其导通时序，从而调整逆变器22输出的有功功率值，实现频率支撑功能。其中，第二载波信号可以是周期固定的正弦波信号或者脉冲信号。
由上述公式二可知，可以利用电网频率的动态变化和逆变器输出的有功功率的动态变换对直流转换器21输出的直流电压进行动态调整。
具体地，第一控制器23利用电压-有功下垂控制策略和电压-频率下垂控制策略共同调整逆变器22接收的直流电压。参见公式二可知，当逆变器22输出的有功功率保持不变时，随着电网频率在[freqmin，freqmax]范围逐步增大，则说明当前电网上传输的有功功率逐渐越多、且超出电网实际需求的有功功率值，为了电网的正常运行，可以增大直流转换器21输出的第一电压幅值，从而降低逆变器22的输出的有功功率。
实际应用时，第一控制器可以跟据第一驱动信号，控制逆变器的运行状态的过程中，定期获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，第三设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
继续参见公式二可知，当电网频率保持不变时，随着逆变器22输出的有功功率逐步增大时，说明光伏发电系统20的产电量逐渐增大时，在不影响电网运行的情况下，可增大直流转换器输出的第一电压幅值，从而控制逆变器22输出的有功功率值单调下降。
实际应用时，第一控制器可以在跟据第一驱动信号控制逆变器的运行状态的过程中，定期获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率加你下。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，第四设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
实施例三
实际应用时，第一控制器23可以利用直流转换器21输出的直流电的第一电压和逆变器22输出的有功功率，生成第一驱动信号。
具体地，第一控制器23根据第二功率差值和第二电压差值，生成第一频率控制信号；根据第一频率控制信号和电网的运行参数，生成第一驱动信号。其中，第二功率差值为逆变器输出的有功功率与第二参考功率之间的差值，第二电压差值为第一电压与第二参考电压之间的差值，第二参考功率为电网正常运行时逆变器输出的额定有功功率值，第二参考电压为电网正常运行时直流转换器输出的额定电压值。
实际使用时，当逆变器22输出的有功功率高于第二参考功率时，则表明逆变器22输出的有功功率高于电网实际需求的有功功率，会造成电网频率上升。当逆变器22输出的有功功率低于第二参考功率时，则表明逆变器22输出的与欧公功率低于电网实际需求的有功功率，会造成电网频率下降。基于上述逆变器22输出的有功功率与电网频率之间的对应关系，建立有功-频率下垂控制策略。同理，当直流转换器21输出的第一电压高于第二参考电压时，则表明电网上传输的功率超出电网实际需求的功率，电网频率上升。当直流转换器21输出的第一电压低于第二参考电压时，则表明电网上传输的功率低于电网实际需求的功率，电网频率下降。基于直流转换器21输出的第一电压与电网频率之间的对应关系，建立电压-频率下垂控制策略，并通过上述两个下垂控制策略计算用于进行频率支撑的频率。
具体地，第一控制器23利用第一功率差值与第三下垂系数得到第一直流电压值；第三下垂系数是根据直流转换器输出的有功功率与直流转换器输出的直流电之间的对应关 系确定的；利用第二频率差值与第四下垂系数得到第二直流电压值；第四下垂系数是根据电网频率与直流转换器输出的直流电之间的对应关系确定的；根据第一直流电压值、第二直流电压值和第三直流电压值，生成第一电压控制信号。其中，第三直流电压值为电站管理系统下发的直流电压初始值，电站管理系统用于控制光伏发电系统的运行状态。
具体地，第一控制器23可以分别与直流传感器和交流传感器连接，直流传感器用于检测直流转换器21输出的第一电压，交流传感器用于检测逆变器22输出的有功功率。
实际使用时，第一控制器23利用逆变器22输出的有功功率的动态变化和直流转换器21输出的第一电压的动态变化，对逆变器22输出的交流电的频率进行动态调整，具体地，第一控制器23采用以下公式计算用于频率支撑的第一频率控制信号：
其中，为生成的第一频率控制信号，为电站管理系统下发的初始频率值。Rfp为第五下垂系数，Rfu为第六下垂系数，PINVRef为第二参考功率，PINV为逆变器输出有功功率。Ubus为第一电压，为第二参考直流电压。
具体地，第五下垂系数是根据逆变器输出的有功功率与电网频率之间的对应关系确定的，第六下垂系数是根据直流转换器输出的直流电与电网频率之间的对应关系确定的。其中，上述数值可以通过比例控制器，积分器、其它组合或者用户选择配置。
参见图2所示，第一控制器23利用上述公式三生成用于实现频率支撑的第一频率控制信号，利用第一频率控制信号以及当前电网的运行参数生成第三调制波信号，该第三调制波信号与第三载波信号比较后生成第一驱动信号，并发送给逆变器22中的开关管，逆变器22中的开关管在上述第二驱动信号的控制下调整其导通时序，从而调整逆变器22输出的有功功率值，实现频率支撑功能。其中，第三载波信号可以是周期固定的正弦波信号或者脉冲信号。
由上述公式三可知，可以利用直流转换器输出的第一电压的动态变化和逆变器输出的有功功率的动态变化对逆变器输出的交流电的频率进行动态变化。
具体地，第一控制器23利用有功-频率下垂控制策略和电压-频率下垂控制策略共同调整逆变器22接收的直流电压。参见公式三可知，当逆变器22输出的有功功率保持不变时，由于直流转换器21工作在MPPT模式下，随着直流母线电压在[Ubusmin，Ubusmax]范围内逐步增大，则说明光伏发电系统20的产电量逐渐增大时，在不影响电网运行的情况下，可以控制逆变器22输出的有功功率值单调上升，逆变器输出的交流电的频率上升，相应的电网频率也会上升。
实际应用时，第一控制器可以在跟据第一驱动信号控制逆变器的运行状态的过程中，定期获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使逆变器输出的交流电的频率上升，以及光伏发电系统输出的有功功率增大。其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及电网频率小于或等于电网正常运行时的频率最大值。第五设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
继续参见公式三可知，当直流转换器输出的第一电压保持不变的情况下，随着逆变器输出的有功功率逐渐增大，则说明当前电网上传输的有功功率超出电网实际需求的有功功 率，电网频率会上升，为了保证电网正常运行，可以控制逆变器22输出的有功功率值单调下降，以及降低逆变器22输出的交流电的频率，从而降低电网频率。
实际应用时，第一控制器可以在跟据第一驱动信号控制逆变器的运行状态的过程中，定期获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使逆变器输出的交流电的频率下降，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，以及所述电网频率大于或等于电网正常运行时的频率最小值。第六设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
应理解，上述三个实施例的描述只是为了分别介绍第一控制器控制光伏发电系统运行的三种方式，上述三个实施例中的第一设定值和第五设定值可以为相同的数值，第二设定值、第三设定值、第四设定值和第六设定值可以为相同的数值。
实际使用时，可以利用上述公式一单独控制逆变器输出的有功功率，也可以采用上述公式二和公式三控制直流电压和频率，实现复合控制。
参见图2和图3所示，逆变器22与直流转换器21连接，逆变器22输出的有功功率主要从直流转换器21上获取，为了实现逆变器22可以快速输出频率支撑所需的有功功率，本申请实施例提供的光伏发电系统20中还可以包括第二控制器，参见图6所示，第二控制器25可以与直流转换器21连接，可以根据第三参考电压与第一电压之间的第三电压差值，生成第二驱动信号，并根据第二驱动信号控制直流转换器21输出的有功功率。其中，第三参考电压为电网正常运行时直流转换器21输出的额定电压。
如前，当电网的频率升高时直流母线电压会上升，以及当电网的频率下降时，直流母线电压会下降。基于上述频率和直流母线电压之间的关系，第二控制器25可以通过检测直流母线电压，确定当前电网的频率，从而输出用于频率支撑的有功功率给逆变器22。
应理解，第二控制器25可以通过电网频率和直流母线电压之间的对应关系，直接通过检测当前直流母线电压进行有功功率调整，从而无需利用高速传输线获取电网侧的频率情况，可以解决直流转换器21频率支撑受限于频率采样性能和高速通讯性能的问题。同时，直流转换器21通过控制直流母线电压可以通过逆变器光伏发电系统产电情况，从而使逆变器可以根据产电情况控制输出至电网的有功功率的多少，并通过电网频率的变换告知电网中连接的其它设备。
具体实现时，第二控制器具体用于：确定直流转换器的工作模式，工作模式包括单向支撑模式和双向支撑模式；根据直流转换器的工作模式和直流转换器的运行参数生成第三参考电压，直流转换器的运行参数包括输入电流、输入电压和输入功率中的一个或多个；根据第三电压差值和第七下垂系数，得到第四功率值，第七下垂系数是根据直流转换器的输出电压和直流转换器输出的有功功率之间的对应关系确定的；根据第四功率值和最大功率值MPPE，确定第二有功功率控制信号；根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号。
在一示例中，第二控制器内还可以包括直流检测单元，用于检测直流母线电压，得到第一电压，并将第一电压输出给第二下垂计算单元。
在另一示例中，第二控制器25与直流传感器连接，直流传感器的信号输入端与直流转换器的输出端连接，直流传感器的信号输出端与第二控制器25连接，第二控制器25通 过直流传感器获取第一电压。
第二下垂计算单元在接收到第一电压以及模式选择单元生成的参考电压后，利用下述公式计算用于实现频率支撑的第二有功功率控制信号：
其中，PBST为生成的第二有功功率控制信号，PMPPE为估算的最大功率值，DPV为第七下垂系数。其中，第七下垂系数DPV可以是但不限于常数、指数和幂指数。
由公式四可知，当光伏组件24的光照情况固定的情况下，最大功率值固定，则直流转换器21输出的有功功率由参考电压决定。
具体地，第二控制器25可以采用以下公式确定第三参考电压
其中，UBstBusRef为设定值，dU(P，Ubus，△P)为动态电压调整值，P为逆变器输出的最大功率值，△P为设定的附加预留功率值。其中，动态电压调整值可以通过比例控制器，积分器或者其它组合获得。
应理解，当光伏组件24的光照情况改变时，则光伏组件24的光电转换效率变换，为了实现光伏发电系统的最大产电量，与光伏组件24连接的直流转换器24通过动态调整其电压值实现工作在MPPT模式。
实际使用时，当直流转换器21工作在单向支撑模式下时，△P为零。当直流转换器21工作在双向支撑模式下时，△P小于最大功率值、且大于零，例如△P可以是最大功率值的10％，然后也可以选用其它数值，例如，最大功率值的15％。其中，设置△P的目的是为了控制直流转换器降功率运行，实现对电网频率的双向支撑。
参见公式五可知，当上述模式选择单元在确定直流转换器工作在单向支撑模式下时，直流转换器的母线参考电压主要由动态电压点确定，即直流转换器21具有功率快速减小的单向支撑能力，但不具备功率快速增大的支撑能力，但是当电网正常运行时，直流转换器可以能够在MPPT模式下运行，以保证光伏发电系统的发电量。
参见图7所示，直流转换器21在O1运行点实现最大功率Pmppt1输出，并兼具单向功率快速支撑能力。当光伏组件24上的光照增强时，MPPT单元的输出功率增大，通过根据公式四和公式五，MPPT单元会使直流转换器21的动态点上移到最大功率点O2点处，即模式选择模块更新直流电压下垂的参考值到U2点，实现直流转换器工作在MPPT模式，并兼具单向功率快速支撑能力。当光伏组件24上的光照减弱时，按照公式二和公式三的计算，会使直流转换器的工作电压下降至最大功率点O3处，实现MPPT模式运行，并兼具单向功率快速支撑能力。
参见公式一至公式五的内容，若直流转换器工作在单向支撑模式，当系统检测到电网频率上升时和电网频率下降时，直流转换器输出的有功功率和逆变器输出的有功功率的波动可参见图8和图9所示。
参见公式五可知，当上述模式选择单元在确定直流转换器工作在双向支撑模式时，直流转换器的母线参考电压不仅由动态点确定，还会利用△P降低附加预留功率值，从而使直流母线的参考电压下降，实现直流转换器工作在功率预留模式，即正常工作时，直流转换器降功率输出。从而在电网频率下降或上升时，可以快速增大或减少其输出的功率，实现双向支撑能力。其中，直流转换器输出的有功功率与直流母线电压之间的对应 关系可参见图10所示。
参见公式一至公式五的内容，若直流转换器工作在双向支撑模式，当系统检测到电网频率上升时和电网频率下降时，直流转换器输出的有功功率和逆变器输出的有功功率的波动可参见图11和图12所示。
其中，直流转换器的工作模式的选择，可以根据用户的选择进行设置，也可以接收上层下发的选择指令进行设置。当然还可以采用其它方式进行设置，例如，直流转换器设置有默认工作模式，当光伏发电系统并网时，可以利用默认工作模式控制直流转换器的运行。
可选的，本申请适用于其它新能源系统的并网架构中，例如，风力发电系统和水利发电系统等，上述新能源系统中均为配置并网逆变器，用于将产生的电能并网的应用场景，也适用于大型储能的应用场景、中小型分布式储能应用场景等。在此仅是举例说明，本申请并不限定具体的应用场景。可选地，本申请也适用于新能源系统的离网场景中。
基于上述光伏发电系统实施例，本申请实施例还提供一种光伏发电系统的控制方法，应用于光伏发电系统中，该方法可以由光伏发电系统中的控制器执行。具体地，光伏发电系统中的控制器包括与逆变器连接的第一控制器。如图13所示，本申请实施例提供的方法具体包括以下步骤：
步骤1301：监控电网的运行参数、直流转换器输出的直流电的第一电压和逆变器输出的有功功率。其中，第一电压为直流转换器输出的直流电的电压幅值，电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一种或多种。
具体实现时，可以利用相应的交流传感器或者直流传感器获取电网的运行参数、第一电压和逆变器输出的有功功率，例如电压传感器和电流传感器。
步骤1302：根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，并根据第一驱动信号控制逆变器的运行状态。
在一种可能的实现方式中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第一电压差值和第一频率差值，生成第一有功功率控制信号，其中，第一电压差值为第一电压与第一参考电压之间的差值，第一频率差值为电网频率与第一参考频率之间的差值，第一参考电压为电网正常运行时直流转换器输出的额定电压值，第一参考频率为电网正常运行时的额定频率值；根据第一有功功率控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的实现方式中，根据第一有功功率控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一有功功率控制信号和电网的运行参数生成第一调制波信号；根据第一调制波信号与第一载波信号，生成第一驱动信号，其中，第一载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的实现方式中，根据第一电压差值和第一频率差值，生成第一有功功率控制信号，包括：利用第一电压差值与第一下垂系数得到第一功率值；第一下垂系数是根据直流转换器的输出的直流电压和直流转换器输出的有功功率之间的对应关系确定；利用第一频率差值与第二下垂系数得到第二功率值；第二下垂系数是根据电网频率与逆变器输出的有功功率之间的对应关系确定的；根据第一功率值、第二功率值和第三功率值，生成第一有功功率控制信号，其中，第三功率值为电站管理系统下发的有功功率初始值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的实现方式，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行 状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，第一设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
在一种可能的实现方式中，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和第一电压；在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使光伏发电系统输出的有功功率口减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，第二设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的实现方式中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第一功率差值和第二频率差值，生成第一电压控制信号，其中，第一功率差值为逆变器输出的有功功率与第一参考功率之间的差值，第二频率差值为电网频率与第二参考频率之间的差值，第一参考功率为电网正常运行时逆变器输出的额定有功功率值，第一参考频率为电网正常运行时的额定频率值；根据第一电压控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的实现方式中，根据第一电压控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一电压控制信号和电网的运行参数生成第二调制波信号；根据第二调制波信号与第二载波信号，生成第一驱动信号，其中，第二载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的实现方式中，根据第一功率差值和第二频率差值，生成第一电压控制信号，包括：利用第一功率差值与第三下垂系数得到第一直流电压值；第三下垂系数是根据直流转换器输出的有功功率与直流转换器输出的直流电之间的对应关系确定的；利用第二频率差值与第四下垂系数得到第二直流电压值；第四下垂系数是根据电网频率与直流转换器输出的直流电之间的对应关系确定的；根据第一直流电压值、第二直流电压值和第三直流电压值，生成第一电压控制信号，其中，第三直流电压值为电站管理系统下发的直流电压初始值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的实现方式中，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，第三设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的实现方式中，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取电网频率和逆变器输出的有功功率；在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使直流转换器输出的第一电压增大，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，第四设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的实现方式中，根据第一电压、逆变器输出的有功功率以及电网的运行参数中的两个，生成第一驱动信号，包括：根据第二功率差值和第二电压差值，生成第一频 率控制信号，其中，第二功率差值为逆变器输出的有功功率与第二参考功率之间的差值，第二电压差值为第一电压与第二参考电压之间的差值，第二参考功率为电网正常运行时逆变器输出的额定有功功率值，第二参考电压为电网正常运行时直流转换器输出的额定电压值；根据第一频率控制信号和电网的运行参数，生成第一驱动信号。
在一种可能的实现方式中，根据第一频率控制信号和电网的运行参数，生成第一驱动信号，包括：根据第一频率控制信号和电网的运行参数生成第三调制波信号；根据第三调制波信号与第三载波信号，生成第一驱动信号，其中，第三载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的实现方式中，根据第二功率差值和第二电压差值，生成第一频率控制信号，包括：利用第二功率差值与第五下垂系数，生成第一频率值，第五下垂系数是根据逆变器输出的有功功率与电网频率之间的对应关系确定的；利用第二电压差值与第六下垂系数，生成第二频率值，第六下垂系数是根据直流转换器输出的直流电与电网频率之间的对应关系确定的；根据第一频率值、第二频率值和第三频率值，生成第一频率控制信号，其中，第三频率值为电站管理系统下发的初始频率值，电站管理系统用于控制光伏发电系统的运行状态。
在一种可能的实现方式中，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整第一驱动信号，以使逆变器输出的交流电的频率上升，以及光伏发电系统输出的有功功率增大。其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及所述电网频率小于或等于电网正常运行时的频率最大值。第五设定值为电网正常运行时光伏发电系统输出的有功功率最大值。
在一种可能的实现方式中，上述控制方法还包括：跟据第一驱动信号控制逆变器的运行状态的过程中，获取第一电压和逆变器输出的有功功率；在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整第一驱动信号，以使逆变器输出的交流电的频率下降，以及光伏发电系统输出的有功功率减小。其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，所述电网频率大于或等于电网正常运行时的频率最小值。第六设定值为电网正常运行时光伏发电系统输出的有功功率最小值。
在一种可能的实现方式中，该方法还包括：根据第一电压和第三电压差值，生成第二驱动信号，并根据第二驱动信号控制直流转换器输出的有功功率，其中，第三电压差值为第三参考电压与第一电压之间的差值，第三参考电压为电网正常运行时直流转换器输出的额定电压。
在一种可能的实现方式中，根据第一电压和第三电压差值，生成第二驱动信号，包括：确定直流转换器的工作模式，工作模式包括单向支撑模式和双向支撑模式；根据直流转换器的工作模式和直流转换器的运行参数生成第三参考电压，直流转换器的运行参数包括输入电流和输入功率中的一个或多个；根据第三电压差值和第七下垂系数，得到第四功率值，第七下垂系数是根据直流转换器的输出电压和直流转换器输出的有功功率之间的对应关系确定的；根据第四功率值和最大功率值MPPE，确定第二有功功率控制信号；根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号。
在一种可能的实现方式中，根据第二有功功率控制信号和直流转换器的输入参数，生成第二驱动信号，包括：根据第二有功功率控制信号与直流转换器的输入参数，生成第四调制波信号；根据第四调制波信号与第四载波信号，生成第二驱动信号，其中，第四载波信号为周期固定的正弦波信号或者脉冲信号。
在一种可能的实现方式中，该方法还包括：根据直流转换器的运行参数确定MPPE。
在一种可能的实现方式中，根据直流转换器的工作模式和直流转换器的运行参数生成第三参考电压，包括：根据直流转换器的工作模式确定附加预留功率值；根据直流转换器的运行参数和附加预留功率值，生成第三参考电压。
结合以上描述，如图14所示，为第一控制器根据第一电压和电网频率生成第一驱动信号的流程示意图，参见图14所示，第一控制器执行以下步骤：
步骤1401：监控电网的运行参数和第一电压。其中，电网的运行参数可以包括有功功率、无功功率、有功电流、无功电流、电网电压和电网频率中的一个或多个。
步骤1402：计算第一电压与第一参考电压之间的第一电压差值，以及电网频率和第一参考频率之间的第一频率差值。
步骤1403：利用第一电压差值和第一频率差值，生成第一有功功率控制信号。
步骤1404：根据第一有功功率控制信号和电网的运行参数生成第一驱动信号。
步骤1405：将第一驱动信号输出给逆变器。
如图15所示，为第一控制器根据逆变器输出的有功功率和电网频率生成第一驱动信号的流程示意图，参见图15所示，第一控制器执行以下步骤：
步骤1501：监控电网的运行参数和逆变器输出的有功功率。其中，电网的运行参数可以包括有功功率、无功功率、有功电流、无功电流、电网电压和电网频率中的一个或多个。
步骤1502：计算逆变器输出的有功功率与第一参考功率之间的第一功率差值，以及电网频率和第二参考频率之间的第二频率差值。
步骤1503：利用第一功率差值和第二频率差值，生成第一电压控制信号。
步骤1504：根据第一电压控制信号和电网的运行参数生成第一驱动信号。
步骤1505：将第一驱动信号输出给逆变器。
如图16所示，为第一控制器根据逆变器输出的有功功率和直流转换器输出的第一电压生成第一驱动信号的流程示意图，参见图16所示，第一控制器执行以下步骤：
步骤1601：监控直流转换器输出的第一电压和逆变器输出的有功功率。
步骤1602：计算第一电压与第二参考电压之间的第二电压差值，以及逆变器输出的有功功率和第二参考功率之间的第二功率差值。
步骤1603：利用第二功率差值和第二电压差值，生成第一频率控制信号。
步骤1604：根据第一频率控制信号和电网的运行参数生成第一驱动信号。
步骤1605：将第一驱动信号输出给逆变器。
实际使用时，逆变器输出的有功功率由直流转换器提供，为了实现频率支撑，直流侧也需要进行输出功率的控制，其中，逆变控制器根据参考电压与直流母线电压之间的第二电压差值，生成第二驱动信号，并根据第二驱动信号控制直流转换器输出的有功功率。
具体地，逆变控制器可以根据第二电压差值和第三下垂系数，得到第四功率值，第三下垂系数是根据直流转换器的输出电压和直流转换器输出的有功功率之间的对应关系确定的；根据第四功率值和最大功率值，确定第二有功功率值；根据第二有功功率控制信号 和直流转换器的输入参数，生成第二驱动信号。
进一步，光伏发电系统中的控制器还包括与直流转换器连接的第二控制器，参见图17所示，本申请实施例提供的方法还包括以下步骤：
步骤1701：监控第一电压。
步骤1702：根据直流转换器的工作模式确定参考电压。
步骤1703：计算第三参考电压与第一电压之间的第三电压差值。
步骤1704：利用第三电压差值和最大功率值，生成第二有功功率控制信号。
步骤1705：根据第二有功功率控制信号和直流转换器的输入参数生成第二驱动信号。
步骤1706：将第二驱动信号发送给直流转换器。
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。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计算机程序指令时，全部或部分地产生按照本申请实施例的流程或功能。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。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，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(digital subscriber line，DSL))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。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括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。可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
本申请实施例还提供一种可读存储介质，用于存储上述实施例提供的方法或算法。例如，随机存取存储器(random access memory，RAM)、闪存、只读存储器(read only memory，ROM)、EPROM存储器、非易失性只读存储器(Electronic Programmable ROM，EPROM)、寄存器、硬盘、可移动磁盘或本领域中其它任意形式的存储媒介。
本申请实施例中所描述的方法或算法的步骤可以直接嵌入控制装置。控制装置可以包括RAM存储器、闪存、ROM存储器、EPROM存储器、寄存器、硬盘、可移动磁盘或本领域中其它任意形式的存储媒介，用于存储本申请实施例提供的方法或算法的步骤。示例性地，存储媒介可以与控制装置中的处理模块或者处理器(或控制器)连接，以使得处理模块、处理器(或控制器)可以从存储媒介中读取信息，并可以向存储媒介存写信息。可选地，存储媒介还可以集成到处理模块、处理器(或控制器)中。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的保护范 围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (42)

  1. 一种光伏发电系统，其特征在于，包括：
    直流转换器，用于连接光伏组件的输出并将所述光伏组件输出的直流电进行电压转换；
    逆变器，用于将所述直流转换器输出的直流电转换为交流电并输出给电网；
    第一控制器，用于根据所述直流转换器输出的直流电的第一电压、所述逆变器输出的有功功率以及所述电网的运行参数中的两个，生成第一驱动信号，并根据所述第一驱动信号控制所述逆变器的运行状态，其中，所述第一电压为所述直流转换器输出的直流电的电压幅值，所述电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一个或多个。
  2. 如权利要求1所述的系统，其特征在于，所述第一控制器具体用于：
    根据第一电压差值和第一频率差值，生成第一有功功率控制信号，其中，所述第一电压差值为所述第一电压与第一参考电压之间的差值，所述第一频率差值为所述电网频率与第一参考频率之间的差值，所述第一参考电压为所述电网正常运行时所述直流转换器输出的额定电压值，所述第一参考频率为所述电网正常运行时的额定频率值；
    根据所述第一有功功率控制信号和所述电网的运行参数，生成所述第一驱动信号。
  3. 如权利要求2所述的系统，其特征在于，所述第一控制器具体用于：
    根据所述第一有功功率控制信号和所述电网的运行参数生成第一调制波信号；
    根据所述第一调制波信号与第一载波信号，生成所述第一驱动信号，其中，所述第一载波信号为周期固定的正弦波信号或者脉冲信号。
  4. 如权利要求2或3所述的系统，其特征在于，所述第一控制器具体用于：
    利用所述第一电压差值与第一下垂系数得到第一功率值；所述第一下垂系数是根据所述直流转换器输出的直流电和所述逆变器输出的有功功率之间的对应关系确定的；
    利用所述第一频率差值与第二下垂系数得到第二功率值；所述第二下垂系数是根据所述电网频率与所述逆变器输出的有功功率之间的对应关系确定的；
    根据所述第一功率值、所述第二功率值和第三功率值，生成所述第一有功功率控制信号，其中，所述第三功率值为电站管理系统下发的有功功率初始值，所述电站管理系统用于控制所述光伏发电系统的运行状态。
  5. 如权利要求2-4任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述第一电压；
    在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整所述第一驱动信号，以使所述光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，所述第一设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最大值。
  6. 如权利要求2-4任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述第一电压；
    在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整所述第一驱动信号，以使所述光伏发电系统输出的有功功率减小，其 中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，所述第二设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  7. 如权利要求1所述的系统，其特征在于，所述第一控制器具体用于：
    根据第一功率差值和第二频率差值，生成第一电压控制信号，其中，第一功率差值为所述逆变器输出的有功功率与第一参考功率之间的差值，所述第二频率差值为所述电网频率与第二参考频率之间的差值，所述第一参考功率为所述电网正常运行时所述逆变器输出的额定有功功率值，所述第一参考频率为所述电网正常运行时的额定频率值；
    根据所述第一电压控制信号和所述电网的运行参数，生成所述第一驱动信号。
  8. 如权利要求7所述的系统，其特征在于，所述第一控制器具体用于：
    根据所述第一电压控制信号和所述电网的运行参数生成第二调制波信号；
    根据所述第二调制波信号与第二载波信号，生成所述第一驱动信号，其中，所述第二载波信号为周期固定的正弦波信号或者脉冲信号。
  9. 如权利要求7或8所述的系统，其特征在于，所述第一控制器具体用于：
    利用所述第一功率差值与第三下垂系数得到第一直流电压值；所述第三下垂系数是根据所述直流转换器输出的有功功率与所述直流转换器输出的直流电之间的对应关系确定的；
    利用所述第二频率差值与所述第四下垂系数得到第二直流电压值；所述第四下垂系数是根据所述电网频率与所述直流转换器输出的直流电之间的对应关系确定的；
    根据所述第一直流电压值、所述第二直流电压值和第三直流电压值，生成所述第一电压控制信号，其中，所述第三直流电压值为电站管理系统下发的直流电压初始值，所述电站管理系统用于控制所述光伏发电系统的运行状态。
  10. 如权利要求7-9任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整所述第一驱动信号，以使所述直流转换器输出的第一电压增大，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，所述第三设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  11. 如权利要求7-9任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整所述第一驱动信号，以使所述直流转换器输出的第一电压增大，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，所述第四设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  12. 如权利要求1所述的系统，其特征在于，所述第一控制器具体用于：
    根据第二功率差值和第二电压差值，生成第一频率控制信号，其中，所述第二功率差值为所述逆变器输出的有功功率与第二参考功率之间的差值，所述第二电压差值为所述第 一电压与第二参考电压之间的差值，所述第二参考功率为所述电网正常运行时所述逆变器输出的额定有功功率值，所述第二参考电压为所述电网正常运行时所述直流转换器输出的额定电压值；
    根据所述第一频率控制信号和所述电网的运行参数，生成所述第一驱动信号。
  13. 如权利要求12所述的系统，其特征在于，所述第一控制器具体用于：
    根据所述第一频率控制信号和所述电网的运行参数生成第三调制波信号；
    根据所述第三调制波信号与第三载波信号，生成所述第一驱动信号，其中，所述第三载波信号为周期固定的正弦波信号或者脉冲信号。
  14. 如权利要求12或13所述的系统，其特征在于，所述第一控制器具体用于：
    利用所述第二功率差值与第五下垂系数，生成第一频率值，所述第五下垂系数是根据所述逆变器输出的有功功率与所述电网频率之间的对应关系确定的；
    利用所述第二电压差值与第六下垂系数，生成第二频率值，所述第六下垂系数是根据所述直流转换器输出的直流电与所述电网频率之间的对应关系确定的；
    根据所述第一频率值、所述第二频率值和第三频率值，生成所述第一频率控制信号，其中，所述第三频率值为电站管理系统下发的初始频率值，所述电站管理系统用于控制所述光伏发电系统的运行状态。
  15. 如权利要求12-14任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述第一电压和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整所述第一驱动信号，以使所述逆变器输出的交流电的频率上升，以及所述光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及所述电网频率小于或等于电网正常运行时的频率最大值，所述第五设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最大值。
  16. 如权利要求12-14任一项所述的系统，其特征在于，所述第一控制器还用于：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述第一电压和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整所述第一驱动信号，以使所述逆变器输出的交流电的频率下降，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，以及所述电网频率大于或等于电网正常运行时的频率最小值，所述第六设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  17. 如权利要求1-16任一项所述的系统，其特征在于，所述光伏发电系统还包括与所述直流转换器连接的第二控制器，用于：根据所述第一电压与第三电压差值，生成第二驱动信号，并根据所述第二驱动信号控制所述直流转换器输出的有功功率，其中，所述第三电压差值为第三参考电压与所述第一电压之间的差值，所述第三参考电压为所述电网正常运行时所述直流转换器输出的额定电压。
  18. 如权利要求17所述的系统，其特征在于，所述第二控制器具体用于：
    确定所述直流转换器的工作模式，所述工作模式包括单向支撑模式和双向支撑模式；
    根据所述直流转换器的工作模式和所述直流转换器的运行参数生成所述第三参考电压，所述直流转换器的运行参数包括输入电流、输入电压和输入功率中的一个或多个；
    根据所述第三电压差值和第七下垂系数，得到第四功率值，所述第七下垂系数是根据所述直流转换器的输出电压和所述直流转换器输出的有功功率之间的对应关系确定的；
    根据所述第四功率值和最大功率值MPPE，确定所述第二有功功率控制信号；
    根据所述第二有功功率控制信号和所述直流转换器的输入参数，生成所述第二驱动信号。
  19. 如权利要求18所述的系统，其特征在于，所述第二控制器具体用于：
    根据所述第二有功功率控制信号与所述直流转换器的输入参数，生成第四调制波信号；
    根据所述第四调制波信号与第四载波信号，生成所述第二驱动信号，其中，所述第四载波信号为周期固定的正弦波信号或者脉冲信号。
  20. 如权利要求18或19所述的系统，其特征在于，所述第二控制器还用于：根据所述直流转换器的运行参数，计算所述MPPE。
  21. 如权利要求17-20任一项所述的系统，其特征在于，所述直流控制器具体用于：
    根据所述直流转换器的工作模式确定附加预留功率值；
    根据所述直流转换器的运行参数和所述附加预留功率值，生成所述第三参考电压。
  22. 一种光伏发电系统的控制方法，其特征在于，应用于光伏发电系统中，包括：
    监控电网的运行参数、直流转换器输出的直流电的第一电压和所述逆变器输出的有功功率；
    根据所述第一电压、所述逆变器输出的有功功率以及所述电网的运行参数中的两个，生成第一驱动信号，并根据所述第一驱动信号控制所述逆变器的运行状态，其中，所述第一电压为所述逆变器输出的直流电的电压幅值，所述电网的运行参数包括无功电流、有功电流、无功功率、有功功率、电压幅值和电网频率中的一个或多个。
  23. 如权利要求22所述的方法，其特征在于，所述根据所述第一电压、所述逆变器输出的有功功率以及所述电网的运行参数中的两个，生成第一驱动信号，包括：
    根据第一电压差值和第一频率差值，生成第一有功功率控制信号，其中，所述第一电压差值为所述第一电压与第一参考电压之间的差值，所述第一频率差值为所述电网频率与第一参考频率之间的差值，所述第一参考电压为所述电网正常运行时所述直流转换器输出的额定电压值，所述第一参考频率为所述电网正常运行时的额定频率值；
    根据所述第一有功功率控制信号和所述电网的运行参数，生成所述第一驱动信号。
  24. 如权利要求23所述的方法，其特征在于，所述根据所述第一有功功率控制信号和所述电网的运行参数，生成所述第一驱动信号，包括：
    根据所述第一有功功率控制信号和所述电网的运行参数生成第一调制波信号；
    根据所述第一调制波信号与第一载波信号，生成所述第一驱动信号，其中，所述第一载波信号为周期固定的正弦波信号或者脉冲信号。
  25. 如权利要求23或24所述的方法，其特征在于，所述根据第一电压差值和第一频率差值，生成第一有功功率控制信号，生成第一驱动信号，包括：
    利用所述第一电压差值与第一下垂系数得到第一功率值；所述第一下垂系数是根据直流转换器的输出的直流电压和所述直流转换器输出的有功功率之间的对应关系确定；
    利用所述第一频率差值与第二下垂系数得到第二功率值；所述第二下垂系数是根据所述电网频率与所述逆变器输出的有功功率之间的对应关系确定的；
    根据所述第一功率值、所述第二功率值和第三功率值，生成所述第一有功功率控制信号，其中，所述第三功率值为电站管理系统下发的有功功率初始值，所述电站管理系统用于控制所述光伏发电系统的运行状态。
  26. 如权利要求23-25任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述第一电压；
    在确定本次与相邻一次获取的电网频率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整所述第一驱动信号，以使所述光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第一设定值，所述第一设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最大值。
  27. 如权利要求23-25任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述第一电压；
    在确定本次与相邻一次获取的第一电压相同、且本次获取的电网频率大于前一次获取的电网频率时，调整所述第一驱动信号，以使所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第二设定值，所述第二设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  28. 如权利要求22所述的方法，其特征在于，所述根据所述第一电压、所述逆变器输出的有功功率以及所述电网的运行参数中的两个，生成第一驱动信号，包括：
    根据第一功率差值和第二频率差值，生成第一电压控制信号，其中，第一功率差值为所述逆变器输出的有功功率与第一参考功率之间的差值，所述第二频率差值为所述电网频率与第二参考频率之间的差值，所述第一参考功率为所述电网正常运行时所述逆变器输出的额定有功功率值，所述第一参考频率为所述电网正常运行时的额定频率值；
    根据所述第一电压控制信号和所述电网的运行参数，生成所述第一驱动信号。
  29. 如权利要求28所述的方法，其特征在于，所述根据所述第一电压控制信号和所述电网的运行参数，生成所述第一驱动信号，包括：
    根据所述第一电压控制信号和所述电网的运行参数生成第二调制波信号；
    根据所述第二调制波信号与第二载波信号，生成所述第一驱动信号，其中，所述第二载波信号为周期固定的正弦波信号或者脉冲信号。
  30. 如权利要求28或29所述的方法，其特征在于，所述根据第一功率差值和第二频率差值，生成第一电压控制信号，包括：
    利用所述第一功率差值与第三下垂系数得到第一直流电压值；所述第三下垂系数是根据所述直流转换器输出的有功功率与所述直流转换器输出的直流电之间的对应关系确定的；
    利用所述第二频率差值与所述第四下垂系数得到第二直流电压值；所述第四下垂系数是根据所述电网频率与所述直流转换器输出的直流电之间的对应关系确定的；
    根据所述第一直流电压值、所述第二直流电压值和第三直流电压值，生成所述第一电压控制信号，其中，所述第三直流电压值为电站管理系统下发的直流电压初始值，所述电 站管理系统用于控制所述光伏发电系统的运行状态。
  31. 如权利要求28-30任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的电网频率大于前一次获取的电网频率时，调整所述第一驱动信号，以使所述直流转换器输出的第一电压增大，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第三设定值，所述第三设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  32. 如权利要求28-30任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述电网频率和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的电网频率相同、且本次获取的逆变器输出的有功功率压大于前一次获取的逆变器输出的有功功率时，调整所述第一驱动信号，以使所述直流转换器输出的第一电压增大，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第四设定值，所述第四设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  33. 如权利要求22所述的方法，其特征在于，所述根据所述第一电压、所述逆变器输出的有功功率以及所述电网的运行参数中的两个，生成所述第一驱动信号，包括：
    根据第二功率差值和第二电压差值，生成第一频率控制信号，其中，所述第二功率差值为所述逆变器输出的有功功率与第二参考功率之间的差值，所述第二电压差值为所述第一电压与第二参考电压之间的差值，所述第二参考功率为所述电网正常运行时所述逆变器输出的额定有功功率值，所述第二参考电压为所述电网正常运行时所述直流转换器输出的额定电压值；
    根据所述第一频率控制信号和所述电网的运行参数，生成所述第一驱动信号。
  34. 如权利要求33所述的方法，其特征在于，所述根据所述第一频率控制信号和所述电网的运行参数，生成所述第一驱动信号，包括：
    根据所述第一频率控制信号和所述电网的运行参数生成第三调制波信号；
    根据所述第三调制波信号与第三载波信号，生成所述第一驱动信号，其中，所述第三载波信号为周期固定的正弦波信号或者脉冲信号。
  35. 如权利要求33或34所述的方法，其特征在于，所述根据第二功率差值和第二电压差值，生成第一频率控制信号，包括：
    利用所述第二功率差值与第五下垂系数，生成第一频率值，所述第五下垂系数是根据所述逆变器输出的有功功率与所述电网频率之间的对应关系确定的；
    利用所述第二电压差值与第六下垂系数，生成第二频率值，所述第六下垂系数是根据所述直流转换器输出的直流电与所述电网频率之间的对应关系确定的；
    根据所述第一频率值、所述第二频率值和第三频率值，生成所述第一频率控制信号，其中，所述第三频率值为电站管理系统下发的初始频率值，所述电站管理系统用于控制所述光伏发电系统的运行状态。
  36. 如权利要求33-35任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述第一电压和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的逆变器输出的有功功率相同、且本次获取的第一电压大于前一次获取的第一电压时，调整所述第一驱动信号，以使所述逆变器输出的交流电的频率上升，以及所述光伏发电系统输出的有功功率增大，其中，调整第一驱动信号后光伏发电系统输出的有功功率小于或等于第五设定值，以及所述电网频率小于或等于电网正常运行时的频率最大值，所述第五设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最大值。
  37. 如权利要求33-35任一项所述的方法，其特征在于，还包括：
    跟据所述第一驱动信号控制所述逆变器的运行状态的过程中，获取所述第一电压和所述逆变器输出的有功功率；
    在确定本次与相邻一次获取的第一电压相同、且本次获取的逆变器输出的有功功率大于前一次获取的逆变器输出的有功功率时，调整所述第一驱动信号，以使所述逆变器输出的交流电的频率下降，以及所述光伏发电系统输出的有功功率减小，其中，调整第一驱动信号后光伏发电系统输出的有功功率大于或等于第六设定值，以及所述电网频率大于或等于电网正常运行时的频率最小值，所述第六设定值为所述电网正常运行时所述光伏发电系统输出的有功功率最小值。
  38. 如权利要求22-37任一项所述的方法，其特征在于，所述方法还包括：
    根据所述第一电压和第三电压差值，生成第二驱动信号，并根据所述第二驱动信号控制所述直流转换器输出的有功功率，其中，第三电压差值为第三参考电压与所述第一电压之间的差值，所述第三参考电压为所述电网正常运行时所述直流转换器输出的额定电压。
  39. 如权利要求28所述的方法，其特征在于，所述根据所述第一电压和第三电压差值，生成第二驱动信号，包括：
    确定所述直流转换器的工作模式，所述工作模式包括单向支撑模式和双向支撑模式；
    根据所述直流转换器的工作模式和所述直流转换器的运行参数生成所述第三参考电压，所述直流转换器的运行参数包括输入电流和输入功率中的一个或多个；
    根据所述第三电压差值和第七下垂系数，得到第四功率值，所述第七下垂系数是根据所述直流转换器的输出电压和所述直流转换器输出的有功功率之间的对应关系确定的；
    根据所述第四功率值和最大功率值MPPE，确定所述第二有功功率控制信号；
    根据所述第二有功功率控制信号和所述直流转换器的输入参数，生成所述第二驱动信号。
  40. 如权利要求39所述的方法，其特征在于，所述根据所述第二有功功率控制信号和所述直流转换器的输入参数，生成所述第二驱动信号，包括：
    根据所述第二有功功率控制信号与所述直流转换器的输入参数，生成第四调制波信号；
    根据所述第四调制波信号与第四载波信号，生成所述第二驱动信号，其中，所述第四载波信号为周期固定的正弦波信号或者脉冲信号。
  41. 如权利要求39或40所述的方法，其特征在于，所述方法还包括：根据所述直流转换器的运行参数确定所述MPPE。
  42. 如权利要求39-41任一项所述的方法，其特征在于，所述根据所述直流转换器的工作模式和所述直流转换器的运行参数生成所述第三参考电压，包括：
    根据所述直流转换器的工作模式确定附加预留功率值；
    根据所述直流转换器的运行参数和所述附加预留功率值，生成所述第三参考电压。
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