WO2024000553A1 - 一种多机光伏组件的等效阻抗测量的光伏系统、方法及光伏功率变换设备 - Google Patents

一种多机光伏组件的等效阻抗测量的光伏系统、方法及光伏功率变换设备 Download PDF

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WO2024000553A1
WO2024000553A1 PCT/CN2022/103214 CN2022103214W WO2024000553A1 WO 2024000553 A1 WO2024000553 A1 WO 2024000553A1 CN 2022103214 W CN2022103214 W CN 2022103214W WO 2024000553 A1 WO2024000553 A1 WO 2024000553A1
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photovoltaic
measurement
measurement signals
frequency
group
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PCT/CN2022/103214
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English (en)
French (fr)
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刘方诚
荣先亮
辛凯
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华为数字能源技术有限公司
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Priority to CN202280006637.4A priority Critical patent/CN116507926A/zh
Priority to PCT/CN2022/103214 priority patent/WO2024000553A1/zh
Publication of WO2024000553A1 publication Critical patent/WO2024000553A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/08—Measuring resistance by measuring both voltage and current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • H02S50/10—Testing of PV devices, e.g. of PV modules or single PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • This application relates to the field of photovoltaics, a photovoltaic system, method and photovoltaic power conversion equipment for equivalent impedance measurement of multi-machine photovoltaic modules.
  • the method of analyzing the health status of photovoltaic modules is based on the equivalent circuit method.
  • the equivalent circuit parameters of the photovoltaic modules are obtained through measurement, and the health status of the photovoltaic modules is judged based on the measured parameters.
  • This method can comprehensively reflect to the health of the photovoltaic modules.
  • the existing photovoltaic module impedance measurement method is mainly an offline photovoltaic module impedance measurement method.
  • This method disconnects the photovoltaic module from the inverter during equivalent impedance measurement, which will affect the overall power generation of the photovoltaic system, as shown in Figure 1
  • the photovoltaic system stops generating electricity to the grid, and the equivalent impedance of the photovoltaic module is calculated by the impedance analyzer. .
  • This application provides an equivalent impedance measurement method of photovoltaic modules, a photovoltaic system and a photovoltaic power conversion equipment, which can measure the equivalent impedance of multiple photovoltaic modules at the same time without causing power fluctuations in the photovoltaic system and thus without affecting the photovoltaic
  • the system's normal power generation has strong applicability.
  • this application provides a method for measuring equivalent impedance of photovoltaic modules.
  • the photovoltaic modules are connected to the power grid through a conversion circuit.
  • the method includes: performing synchronous phase-shifted impedance measurements on N (N is an integer greater than or equal to 2) photovoltaic modules at the same time, the output end of each photovoltaic module is connected to the input end of the corresponding conversion circuit, and the output ends of the N conversion circuits In series, each of the conversion circuits is connected to the controller.
  • the photovoltaic module of the photovoltaic system When the average output voltage of the photovoltaic module is maintained within a certain range, that is, the photovoltaic module of the photovoltaic system is in normal working condition, and its output voltage maintains normal fluctuations, and The fluctuation range is within the threshold range set by the photovoltaic system and will not affect the normal operation of the photovoltaic system. In this medium state, the photovoltaic system generates AC measurement signals of N photovoltaic modules.
  • the AC measurement signals of the N photovoltaic modules The amplitude superposition within one cycle cancels each other out; load the AC measurement signals of N photovoltaic modules into their respective conversion circuits, and then obtain the output voltage and output current of N photovoltaic modules at the corresponding frequency of their respective AC measurement signals, thereby simultaneously Determine the equivalent impedance of N photovoltaic modules.
  • the method can load AC measurement signals whose amplitudes are superimposed and cancel each other in the same periodic signal into N conversion circuits respectively, so that each conversion circuit corresponds to the value of the connected photovoltaic module.
  • the output voltage and output current include a frequency component corresponding to the AC measurement signal, and the equivalent impedance of the corresponding photovoltaic module is determined based on the frequency component corresponding to the AC measurement signal.
  • the method in this application can complete the measurement of the equivalent impedance of N photovoltaic modules without causing power fluctuations in the photovoltaic system, thereby not affecting the normal power generation of the photovoltaic system, and has strong applicability.
  • AC measurement signals of N photovoltaic modules are generated, and the frequency of the AC measurement signals of the N photovoltaic modules is consistent and is the first frequency; at the same time, these N photovoltaic modules
  • the phases of the AC measurement signals are different.
  • the phases of any two adjacent AC measurement signals differ by 360 0 /N in sequence. It can be understood that the generated N modules have the same frequency and the phase differs in sequence by 360 0 /N.
  • the amplitudes of these N AC measurement signals are superimposed and cancel each other out in the same cycle. Therefore, they will not cause power fluctuations in the electric energy transmitted from the photovoltaic system to the grid. It can measure N photovoltaic modules at the same time while ensuring the safety of the photovoltaic system. normal operation.
  • AC measurement signals of N photovoltaic modules are generated.
  • M is an integer greater than or equal to 2 and less than N; the AC measurement signals of M groups of photovoltaic modules, in terms of frequency, the frequency within the group is consistent with that between the groups, which is the first Frequency; in terms of amplitude, the amplitudes within the group and between groups are consistent, which is the first amplitude; in terms of phase, the initial phase within the group is consistent, and the initial phase between groups is different.
  • the phases of any adjacent two groups of AC measurement signals are sequentially different. 360 0 /M.
  • the photovoltaic power conversion equipment for the AC measurement signals of N photovoltaic modules is divided into M groups.
  • the AC measurement signals of the M groups of photovoltaic modules have the same frequency and the phase difference between the groups is 360 0 /M.
  • the amplitudes cancel each other out, so they will not cause power fluctuations in the electric energy transmitted from the photovoltaic system to the grid, and ensure the normal operation of the photovoltaic system while measuring N photovoltaic modules at the same time.
  • AC measurement signals of N photovoltaic modules are generated.
  • the AC measurement signals of the N photovoltaic modules are divided into M groups.
  • M is an integer greater than or equal to 2 and less than N.
  • Each group contains Z AC measurement signals.
  • Z is an integer greater than or equal to 1.
  • the number of Z in each group is It can be different; in terms of frequency, the AC measurement signal of M groups of photovoltaic modules is the same within each group, and the frequency between each group is the same or different; in terms of phase, the initial phase in each group is different, and any phase in the group
  • the phases of two adjacent AC measurement signals differ by 360 0 /Z. It can be understood that N photovoltaic power conversion devices are divided into M groups.
  • the AC measurement signals of the photovoltaic modules have the same frequency and a phase difference of 360 0 /Z.
  • the amplitudes cancel each other out, and thus in the superposition of AC signals between M groups, the amplitudes also cancel each other out. Therefore, it will not cause power fluctuations in the electric energy transmitted from the photovoltaic system to the grid, and ensure the normal operation of the photovoltaic system while measuring N photovoltaic modules at the same time.
  • AC measurement signals of N photovoltaic modules are generated.
  • the AC measurement signals of the N photovoltaic modules are divided into M groups.
  • M is an integer greater than or equal to 2 and less than N.
  • Each group contains Z AC measurement signals.
  • Z is an integer greater than or equal to 1.
  • the number of Z in each group is It can be different; the AC measurement signals of M groups of photovoltaic modules have the same frequency within each group and between groups; the amplitude A can be different within the group and between groups, and each AC measurement signal within the group in different groups The sum of the amplitudes A of is equal between groups.
  • the sum of the amplitudes A of the AC measurement signals in the first group is equal to the sum of the amplitudes A of the AC measurement signals in the second group.
  • the sum of the amplitudes A of the AC measurement signals in the Mth group is equal to the amplitude A of the AC measurement signals in the Mth group.
  • the initial phase within each group is the same, and the phases of any two adjacent groups of AC measurement signals differ by 360 0 /M in sequence. It can be understood that N photovoltaic power conversion equipment is divided into M groups.
  • the AC measurement signals of the N photovoltaic modules have the same frequency.
  • the AC measurement signals of the N photovoltaic modules are divided into M groups.
  • the N conversion circuits are also divided into M groups, and the M groups of AC measurement signals are divided into M groups.
  • the signals correspond to M groups of conversion circuits one-to-one.
  • One group of conversion circuits is the main measurement group, and the remaining groups of conversion circuits are slave measurement groups.
  • the main measurement group first starts photovoltaic equivalent impedance measurement, generates AC measurement signals, and loads the AC measurement signals.
  • the main measurement group uses other communication means such as PLC communication or other wired communication or wireless communication such as wifi communication to actively send the measurement start signal to the slave Measurement group; receive the measurement start signal sent by the main measurement group from the measurement group, start the photovoltaic equivalent impedance measurement from each slave measurement group, generate an AC measurement signal, and load the AC measurement signal into each slave measurement group to the conversion circuit, Perform equivalent impedance measurements of photovoltaic modules.
  • the AC measurement signals of the N photovoltaic modules are divided into M groups.
  • the N conversion circuits are also divided into M groups, and the M groups of AC measurement signals are divided into M groups.
  • the signals correspond to M groups of conversion circuits one-to-one.
  • One group of conversion circuits is the main measurement group, and the remaining groups of conversion circuits are slave measurement groups.
  • the main measurement group first starts photovoltaic equivalent impedance measurement, generates AC measurement signals, and loads the AC measurement signals.
  • the photovoltaic module impedance measurement is performed; the slave measurement group actively detects the bus port voltage fluctuation, and the frequency of the bus port voltage fluctuation is the set frequency of the AC measurement signal of the main measurement group; the slave measurement group After the group detects the voltage fluctuation of the bus port, it confirms that the photovoltaic system starts multi-machine photovoltaic equivalent impedance measurement. Therefore, the slave measurement group starts the photovoltaic equivalent impedance measurement each, generates an AC measurement signal, and loads the AC measurement signal to the transformation of each slave measurement group. In the circuit, the equivalent impedance measurement of the photovoltaic module is performed.
  • the AC measurement signals of the N photovoltaic modules are divided into M groups.
  • the N conversion circuits are also divided into M groups, and the M groups of AC measurement signals are divided into M groups.
  • Signals correspond to M groups of conversion circuits one-to-one, one group of conversion circuits is the master measurement group, and the remaining groups of conversion circuits are slave measurement groups.
  • the main measurement group first starts the photovoltaic equivalent impedance measurement, and the slave measurement groups start the photovoltaic equivalent impedance measurement respectively after the main measurement group starts.
  • the slave measurement group performs phase compensation on the AC measurement signals generated by the slave measurement group based on the startup delay between the slave measurement group and the master measurement group, so that the AC measurement signals corresponding to the slave measurement group and the master measurement group are in the same cycle.
  • the amplitudes within the superposition cancel each other out.
  • equivalent impedance measurements are performed on the N photovoltaic components, and the AC measurement signals of the N photovoltaic components are loaded into the corresponding conversion circuits in sequence.
  • one of the N conversion circuits is set as the master measurement conversion circuit, and the remaining conversion circuits are set as slave measurement conversion circuits.
  • the main measurement conversion circuit first starts the photovoltaic module equivalent impedance measurement, and the slave measurement conversion circuits respectively start the photovoltaic module equivalent impedance measurement after the main measurement conversion circuit starts.
  • the information synchronization method between the master and slave measurement conversion circuits is the same as the synchronization method of the master and slave measurement groups in the sixth and seventh possible implementation manners of the first aspect; due to the existence of startup time between the master and slave measurement conversion circuits, Therefore, when the equivalent impedance measurement is started from the slave measurement conversion circuit, the AC measurement signal corresponding to the slave measurement conversion circuit is phase compensated, so that the AC measurement signal corresponding to the slave measurement conversion circuit is the same as the AC measurement corresponding to the main measurement conversion circuit. The superposition of signal amplitudes within the same period cancel each other out.
  • the conversion circuit is a DC/DC conversion circuit
  • the photovoltaic system further includes a positive and negative DC bus
  • N DC/DC conversion circuits are connected in series
  • N The DC/DC conversion circuits are connected in series between the positive and negative DC buses.
  • the DC/DC conversion circuit includes a Boost circuit
  • the Boost circuit includes a first inductor and a first switch tube.
  • the positive input terminal of the Boost circuit is connected to the negative output terminal of the Boost circuit through the first inductor and the first switch tube.
  • the driving signal is used to control the on and off of the first switch tube in the Boost circuit, thereby controlling the output voltage of the photovoltaic module.
  • the conversion circuits are respectively DC/AC inverter circuits
  • the photovoltaic system further includes positive and negative AC bus bars
  • N DC/AC inverter circuits are connected in series. Connection, N pieces of the DC/AC inverter circuits are connected in series to the positive and negative AC buses.
  • the inverter circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm. The first phase bridge arm, the second phase bridge arm and the third phase bridge arm are all connected in parallel to the input end of the inverter circuit, and the driving signal includes a first driving sub-signal, a second driving sub-signal and a third driving sub-signal.
  • the AC measurement signals of N photovoltaic modules are loaded into their respective conversion circuits.
  • the reference voltage of each conversion circuit and the corresponding AC measurement signal are superimposed to obtain a second reference voltage; the second reference voltage and the corresponding photovoltaic module are used.
  • the current output voltage generates a first modulated wave, and the driving signal is generated according to the first modulated wave.
  • the output voltages and output currents of the N photovoltaic modules are controlled by the driving signal and frequency domain filtered based on the corresponding frequencies of the N AC measurement signals to obtain the output voltage and output current of the N photovoltaic modules in the N
  • the output voltage and output current of each corresponding frequency of the AC measurement signal; based on the output voltage and output current of the N photovoltaic modules at the corresponding frequency of each AC measurement signal, the equivalent impedance of the N photovoltaic modules is determined respectively.
  • the AC measurement signal is directly loaded into the conversion circuit through the driving voltage, so that the output current and output voltage of the photovoltaic module include the frequency component of the AC measurement signal, and finally the equivalent impedance under the frequency component is obtained to achieve Online measurement of the equivalent impedance of photovoltaic modules does not affect the normal power generation of the photovoltaic system and has strong applicability.
  • the AC measurement signals of N photovoltaic modules are loaded into respective conversion circuits.
  • each AC measurement signal and the reference voltage of its respective corresponding conversion circuit and the output voltage of the photovoltaic module respectively generate N driving signals, wherein the AC measurement signal of each photovoltaic module contains at least two different frequencies, and the at least two different frequencies are the first frequency and the second frequency respectively; respectively obtained here
  • the output voltage and output current of N photovoltaic modules under the control of N driving signals are then filtered in the frequency domain based on the first frequency and the second frequency corresponding to the AC measurement signal respectively, and N under the control of N driving signals are obtained.
  • the equivalent impedance of the component at at least two different frequencies can effectively reduce the workload and improve work efficiency. At the same time, it can effectively improve the measurement accuracy of the equivalent impedance of the photovoltaic component and has strong applicability.
  • the first frequency components of each of the AC measurement signals cancel each other out in amplitude superposition within the same period; the second frequency components of each of the AC measurement signals The amplitude superpositions within the same period cancel each other out; or the amplitude superpositions of each AC measurement signal including the first frequency component and the second frequency component within the same period cancel each other out.
  • equivalent impedances at at least two different frequencies can be obtained simultaneously through one equivalent impedance measurement to improve the efficiency and accuracy of the measurement.
  • the premise is to ensure that the amplitude superposition of all measurement signals at different frequencies cancels each other out, thereby not causing The output power of photovoltaic systems fluctuates.
  • the current working state of each conversion circuit is determined, and respective reference voltages are determined according to the current working state of each conversion circuit, and each reference voltage is They are respectively the reference input voltage of the corresponding conversion circuit in the power-limited operating state, or the reference input voltage of each corresponding conversion circuit in the non-power-limited operating state.
  • the N reference voltages change with the current working state of the corresponding conversion circuit (i.e., the power-limited working state or the non-power-limited working state). Therefore, it can effectively satisfy the needs of the N photovoltaic power conversion devices.
  • the demand for power supply to the grid under different working conditions has high flexibility.
  • the amplitudes of the AC measurement signals of the N photovoltaic modules in the same period cancel each other. It can be understood that the N AC measurement signals are superimposed on each other. The amplitude after is zero or less than or equal to the set threshold.
  • the fluctuations caused by N AC measurement signals will not exceed the operating state of the photovoltaic system. The normal power fluctuation can ensure that when the photovoltaic system is working normally, the equivalent impedance of N photovoltaic modules can be obtained at the same time.
  • the amplitude of the one AC measurement signal is less than or equal to the set threshold, so a single AC measurement signal will not cause damage to the photovoltaic system. Power fluctuations in normal operating conditions exceed the normal range. It can be understood that the superimposed signal of the N AC measurement signals will not exceed the set threshold, which allows greater flexibility in setting the frequency, amplitude, and phase of the N AC measurement signals.
  • this application provides a photovoltaic system that can simultaneously measure the equivalent impedance of N photovoltaic strings in the system without causing drastic fluctuations in the output power of the photovoltaic system.
  • the photovoltaic system includes N conversion circuits and at least one controller, where N is an integer greater than or equal to 2; the input end of each conversion circuit is connected to a corresponding photovoltaic component, and the photovoltaic components correspond to the conversion circuit one-to-one.
  • the output ends of the N conversion circuits are connected in series, the first end and the second end of the N conversion circuits that are not connected in series are connected to the power grid, and each of the conversion circuits is connected to the at least one controller; the photovoltaic system can simultaneously N (N is greater than or equal to 2) photovoltaic modules perform equivalent impedance measurement. At least one controller in the photovoltaic system generates AC measurement signals of N photovoltaic modules. The phases of the AC measurement signals of the N photovoltaic modules are different.
  • the N photovoltaic modules The amplitudes of the AC measurement signals of the components in the same cycle are superimposed to cancel each other out; the at least one controller loads the AC measurement signals of the N photovoltaic components into their respective corresponding conversion circuits, so that the photovoltaic cells connected to each conversion circuit
  • the output voltage and output current of the module include frequency components corresponding to the respective AC measurement signals, and the equivalent impedances of the N photovoltaic modules are determined based on the frequency components corresponding to the respective AC measurement signals.
  • At least one controller in the photovoltaic system generates AC measurement signals of N photovoltaic modules respectively, and the AC measurement signals of the N photovoltaic modules have the same frequency, which is the first frequency; at the same time, the phases of the AC measurement signals of these N photovoltaic modules are different.
  • the phases of any two adjacent AC measurement signals among the AC measurement signals of N photovoltaic modules differ by 360 0 /N in turn; it can be understood that the phase difference in the photovoltaic system
  • At least one controller generates AC measurement signals of N photovoltaic modules with the same frequency and a phase difference of 360 0 /N.
  • the amplitudes of these N AC measurement signals are superimposed and cancel each other out in the same cycle, so they will not cause the photovoltaic system to transmit to the grid.
  • the power fluctuation of transmitted electric energy is measured simultaneously to ensure the normal operation of the photovoltaic system while measuring N photovoltaic modules.
  • At least one controller of the photovoltaic system generates AC measurement signals of N photovoltaic modules respectively.
  • the photovoltaic system divides the AC measurement signals of N photovoltaic modules into M groups, M is an integer greater than or equal to 2 and less than N; the AC measurement signals of the M groups of photovoltaic modules have the same frequency within the group and between the groups, as The first frequency; in terms of amplitude, the amplitudes within the group and between groups are consistent, which is the first amplitude; in terms of phase, the initial phase within the group is consistent, and the initial phase between groups is different, and any adjacent two groups between the groups are measured interchangeably
  • the phases of the signals differ by 360 0 /M in turn.
  • the photovoltaic system divides the AC measurement signals of N photovoltaic modules into M groups.
  • the AC measurement signals of the M groups of photovoltaic modules have the same frequency and a phase difference of 360 0 /M between the groups.
  • the communication between the groups In the superposition of measurement signals, the amplitudes cancel each other out, so they will not cause power fluctuations in the electric energy transmitted from the photovoltaic system to the grid, and ensure the normal operation of the photovoltaic system while measuring N photovoltaic modules at the same time.
  • At least one controller of the photovoltaic system generates AC measurement signals of N photovoltaic modules respectively.
  • the photovoltaic system divides the AC measurement signals of N photovoltaic modules into M groups, M is an integer greater than or equal to 2 and less than N.
  • Each group contains Z AC measurement signals, Z is an integer greater than or equal to 1, and Z in each group
  • the numbers can vary; in terms of frequency, the AC measurement signals of M groups of photovoltaic modules are the same within each group, and the frequencies between each group are the same or different; in terms of phase, the initial phases within each group are different, and any value within the group
  • the phases of two adjacent AC measurement signals differ by 360 0 /Z.
  • the photovoltaic system divides the AC measurement signals of N photovoltaic power conversion equipment components into M groups. Within each M group, the AC measurement signals of the photovoltaic components have the same frequency and a phase difference of 360 0 /Z. In the superposition of AC measurement signals within a group, the amplitudes cancel each other out, and thus in the superposition of AC signals between M groups, the amplitudes also cancel each other out. Therefore, it will not cause power fluctuations in the electric energy transmitted from the photovoltaic system to the grid, and ensure the normal operation of the photovoltaic system while measuring N photovoltaic modules at the same time.
  • At least one controller of the photovoltaic system generates AC measurement signals of N photovoltaic components respectively.
  • the AC measurement signals of N photovoltaic modules in the photovoltaic system are divided into M groups, M is greater than or equal to 2, each group contains Z AC measurement signals, Z is an integer greater than or equal to 1, and the number of Z in each group can vary;
  • the AC measurement signals of M groups of photovoltaic modules have the same frequency within each group and between groups; the amplitude A can be different within a group and between groups.
  • the amplitude A of each AC measurement signal within a group in different groups The sum is equal between groups, that is, the sum of the amplitudes A of the AC measurement signals in the first group is equal to the sum of the amplitudes A of the AC measurement signals in the second group, which is equal to the sum of the amplitudes A of the AC measurement signals in the Mth group;
  • the initial phase within each group is the same, and the phases of any adjacent two groups of AC measurement signals differ by 360 0 /M between groups. It can be understood that the photovoltaic system divides the AC measurement signals of N photovoltaic modules into M groups.
  • the AC measurement signals of the N photovoltaic modules have the same frequency.
  • the photovoltaic system divides the AC measurement signals of the N photovoltaic modules into M groups. Similarly, the photovoltaic system also divides the N conversion circuits into M groups. M groups of AC measurement signals correspond to M groups of conversion circuits one-to-one. One group of conversion circuits is the master measurement group, and the remaining groups of conversion circuits are slave measurement groups.
  • the master measurement group first starts photovoltaic equivalent impedance measurement, generates AC measurement signals, and The AC measurement signal is loaded into the conversion circuit of the main measurement group to measure the photovoltaic module impedance; while starting the measurement, the main measurement group uses wired communication such as PLC communication or wireless communication such as WiFi communication or other communication means to actively transmit the measurement start signal Send to the slave measurement group; the slave measurement group receives the measurement start signal sent by the main measurement group, each slave measurement group starts the photovoltaic equivalent impedance measurement, generates an AC measurement signal, and loads the AC measurement signal to each slave measurement group to the photovoltaic In the module, the equivalent impedance of the photovoltaic module is measured from the measurement group.
  • wired communication such as PLC communication or wireless communication such as WiFi communication or other communication means to actively transmit the measurement start signal Send to the slave measurement group
  • the slave measurement group receives the measurement start signal sent by the main measurement group, each slave measurement group starts the photovoltaic equivalent impedance measurement, generates an AC measurement signal, and loads the AC measurement
  • the photovoltaic system divides the AC measurement signals of the N photovoltaic modules into M groups. Similarly, the photovoltaic system also divides the N conversion circuits into M groups. M groups of AC measurement signals correspond to M groups of conversion circuits one-to-one. One group of conversion circuits is the master measurement group, and the remaining groups of conversion circuits are slave measurement groups.
  • the master measurement group first starts photovoltaic equivalent impedance measurement, generates AC measurement signals, and The AC measurement signal is loaded into the conversion circuit of the main measurement group to measure the photovoltaic module impedance; the slave measurement group actively detects the bus port voltage fluctuation, and the frequency of the bus port voltage fluctuation is the set frequency of the AC measurement signal of the main measurement group; After the slave measurement group detects the bus port voltage fluctuation, it is confirmed that the photovoltaic system starts multi-machine photovoltaic equivalent impedance measurement. Therefore, the slave measurement group starts the photovoltaic equivalent impedance measurement individually, generates AC measurement signals, and loads the AC measurement signals to each slave measurement group. Go to the conversion circuit and measure the impedance of the photovoltaic module.
  • the photovoltaic system divides the AC measurement signals of the N photovoltaic modules into M groups. Similarly, the photovoltaic system also divides the N conversion circuits into M groups. It is an M group, and the M group of AC measurement signals corresponds to the M group of conversion circuits one-to-one. One group of conversion circuits is the master measurement group, and the remaining groups of conversion circuits are the slave measurement groups. The main measurement group first starts the photovoltaic equivalent impedance measurement, and the slave measurement groups start the photovoltaic equivalent impedance measurement respectively after the measurement group is started.
  • the slave measurement group in the photovoltaic system performs phase compensation on the AC measurement signal generated by the slave measurement group, so that the slave measurement group is in line with the master measurement group.
  • the amplitude superposition of the corresponding AC measurement signals in the same period cancels each other out.
  • the photovoltaic system performs equivalent impedance measurement on the N photovoltaic components.
  • the photovoltaic system performs equivalent impedance measurement on different photovoltaic components. There are differences in the starting sequence for practical applications. .
  • the photovoltaic system sets one of the N conversion circuits as a master measurement conversion circuit, and the remaining conversion circuits are set as slave measurement conversion circuits.
  • the main measurement conversion circuit first starts the photovoltaic module equivalent impedance measurement, and the slave measurement conversion circuits respectively start the photovoltaic module equivalent impedance measurement after the main measurement conversion circuit starts.
  • the information synchronization method between the master and slave measurement conversion circuits in the photovoltaic system is the same as the synchronization method of the master and slave measurement groups in the sixth and seventh possible implementation manners of the first aspect; Due to the startup delay between the master and slave measurement conversion circuits, when the slave measurement conversion circuit starts the equivalent impedance measurement, the volt system performs phase compensation on the AC measurement signal corresponding to the slave measurement conversion circuit, so that the slave measurement conversion circuit The amplitude superposition of the AC measurement signal corresponding to the circuit and the AC measurement signal corresponding to the main measurement conversion circuit in the same cycle cancels each other out.
  • the conversion circuit in the photovoltaic system is a DC/DC conversion circuit
  • the photovoltaic system further includes positive and negative DC bus bars, and N number of the DC/DC conversion circuits.
  • the N DC/DC conversion circuits are connected in series between the positive and negative DC buses.
  • the DC/DC conversion circuit includes a Boost circuit
  • the Boost circuit includes a first inductor and a first switch tube.
  • the positive input terminal of the Boost circuit is connected to the negative output terminal of the Boost circuit through the first inductor and the first switch tube.
  • the photovoltaic system controls the on and off of the first switch tube according to the driving signal, thereby controlling the output voltage of the photovoltaic module.
  • the conversion circuits in the photovoltaic system are respectively DC/AC inverter circuits, and the photovoltaic system further includes positive and negative AC bus bars, N DC/AC The inverter circuits are connected in series, and N DC/AC inverter circuits are connected in series between the positive and negative AC buses.
  • the inverter circuit includes a first phase bridge arm, a second phase bridge arm and a third phase bridge arm. The first phase bridge arm, the second phase bridge arm and the third phase bridge arm are all connected in parallel to the input end of the inverter circuit, and the driving signal includes a first driving sub-signal, a second driving sub-signal and a third driving sub-signal.
  • the photovoltaic power conversion equipment controls the conduction time of the switch tube of the first phase bridge arm and the conduction time of the switch tube of the second phase bridge arm according to the first drive sub-signal, the second drive sub-signal and the third drive sub-signal respectively. and the conduction time of the switch tube of the third phase bridge arm, thereby controlling the output voltage of the photovoltaic module.
  • the photovoltaic system loads the AC measurement signals of N photovoltaic modules into respective conversion circuits.
  • at least one controller determines the AC measurement signals according to each AC measurement signal and its corresponding The reference voltage of the conversion circuit and the output voltage of the photovoltaic module generate N driving signals respectively.
  • the photovoltaic system superimposes the reference voltage of each conversion circuit and the corresponding AC measurement signal to obtain a second reference voltage; then the photovoltaic system uses the The second reference voltage and the current output voltage of the corresponding photovoltaic component generate a first modulated wave, and finally the photovoltaic system generates the driving signal according to the first modulated wave.
  • the photovoltaic system generates a second modulated wave by using the reference voltage of each conversion circuit and the current output voltage of the corresponding photovoltaic component; and then the photovoltaic system superposes the second modulated wave and the corresponding AC measurement signal to obtain A third modulated wave, and finally the photovoltaic system generates the driving signal according to the third modulated wave.
  • the N driving signals are used to control the output voltages of N photovoltaic components in the photovoltaic system, where the N reference voltages are the reference input voltages of each of the N conversion circuits in the photovoltaic system when supplying power to the power grid.
  • the at least one controller obtains the output voltage and output current of the N photovoltaic modules under the control of the N driving signals, and performs the output voltage and output current of the N photovoltaic modules based on the respective corresponding frequencies of the N AC measurement signals. Frequency domain filtering is used to obtain the output voltage and output current of the N photovoltaic modules at the corresponding frequencies of the N AC measurement signals; the at least one controller is based on the output voltage of the N photovoltaic modules at the corresponding frequencies of the respective AC measurement signals. and output current, respectively determine the equivalent impedance of N photovoltaic modules.
  • the AC measurement signal is directly loaded into the conversion circuit through the driving voltage, so that the output current and output voltage of the photovoltaic module include the frequency component of the AC measurement signal, and finally the equivalent impedance under the frequency component is obtained to achieve Online measurement of the equivalent impedance of photovoltaic modules does not affect the normal power generation of the photovoltaic system and has strong applicability.
  • the photovoltaic system loads the AC measurement signals of N photovoltaic modules into respective conversion circuits.
  • at least one controller determines the AC measurement signals according to each AC measurement signal and its corresponding The reference voltage of the conversion circuit and the output voltage of the photovoltaic module respectively generate N driving signals, wherein the AC measurement signal of each photovoltaic module each contains at least two different frequencies, and the at least two different frequencies are the first frequency and the second frequency respectively. Frequency; the at least one controller obtains the output voltage and output current of the N photovoltaic modules under the control of the N driving signals, and then frequency based on the first frequency and the second frequency corresponding to the AC measurement signal.
  • the photovoltaic system can centrally inject at least two AC measurement signals of different frequencies into the conversion circuit at one time, and the at least one controller can then obtain the output of each photovoltaic module at each of the at least two different frequencies at one time. voltage and output current.
  • determining the equivalent impedance of N photovoltaic modules at at least two different frequencies at one time can effectively reduce the workload and improve work efficiency. At the same time, it can effectively improve the measurement accuracy of the equivalent impedance of photovoltaic modules. Strong applicability.
  • the first frequency components of each of the AC measurement signals are superimposed in amplitude and cancel each other out in the same period; each of the AC measurement signals The superimposed amplitudes of the second frequency components in the same period cancel each other out; or the superimposed amplitudes of each AC measurement signal containing the first frequency component and the second frequency component in the same period cancel each other out.
  • the photovoltaic system can simultaneously obtain at least two equivalent impedances at different frequencies through one equivalent impedance measurement, thereby improving the efficiency and accuracy of the measurement.
  • the premise is to ensure that the amplitude superposition of all measurement signals at different frequencies cancels each other out. This will not cause fluctuations in the output power of the photovoltaic system.
  • the photovoltaic system determines the current working status of each conversion circuit, and determines its respective reference voltage according to the current working status of each conversion circuit.
  • the reference voltages are respectively the reference input voltage of the corresponding conversion circuit in the power-limited operating state, or the reference input voltage of each photovoltaic power conversion device in the non-power-limited operating state. It can be understood that the N reference voltages of the photovoltaic system change with the current working state of the corresponding conversion circuit (i.e., the power-limited working state or the non-power-limited working state). Therefore, the N reference voltages can be effectively satisfied respectively.
  • Photovoltaic power conversion equipment has high flexibility in supplying power to the grid under different working conditions.
  • the controller in the photovoltaic system can be as described in the above implementation manner, each conversion circuit corresponds to a controller, and the controller and the conversion circuit One-to-one correspondence, so that each controller independently controls a conversion circuit, with high flexibility and various control methods.
  • a centralized control method can be used, that is, a controller centrally controls each conversion circuit, and each conversion circuit adopts centralized control.
  • the controller in the photovoltaic system can make decisions based on global information. Optimal control improves system performance as a whole and makes it more efficient.
  • the amplitudes of the AC measurement signals of the N photovoltaic components in the photovoltaic system cancel each other in the same cycle.
  • the N AC The amplitude of the superimposed signal formed after the measurement signals are superimposed on each other is zero or less than or equal to the set threshold.
  • the above second aspect sets the frequency, amplitude and phase of the N AC measurement signals based on the superimposed signal being zero.
  • the photovoltaic system can also set the frequency, amplitude and phase of the N AC measurement signals based on the amplitude of the superimposed signal being less than or equal to the set threshold. It can be understood that by setting the objective function more relaxedly, the range of feasible solutions can be further expanded.
  • the photovoltaic system is more flexible and diverse when setting N AC measurement signals.
  • the threshold set by the photovoltaic system is used to measure the equivalent impedance of N photovoltaic modules at the same time, the fluctuations caused by the N AC measurement signals will not exceed the normal power fluctuations of the photovoltaic system under working conditions. Therefore, It can be ensured that when the photovoltaic system is operating normally, the equivalent impedance of N photovoltaic modules can be obtained at the same time.
  • the amplitude of the one AC measurement signal is less than or equal to the set threshold, so the single AC measurement signal will not cause the The power fluctuation of the photovoltaic system under normal operating conditions exceeds the normal range.
  • the present application provides a photovoltaic power conversion device.
  • the photovoltaic power conversion device includes a conversion circuit, a controller, an input terminal and an output terminal.
  • the input terminal is connected to the output terminal of the corresponding photovoltaic component.
  • the output terminal is connected to a voltage bus or other photovoltaic power conversion equipment, and the conversion circuit is a DC/DC conversion circuit or a DC/AC inverter circuit; the controller adopts the method provided by any possible implementation of the first aspect.
  • Equivalent impedance measurement method of multi-machine photovoltaic modules the controller includes:
  • the controller is used to generate at least one AC measurement signal when the average output voltage of the photovoltaic module is maintained within a certain range.
  • the frequency, amplitude and phase of the AC measurement signal can be set, and the phases of the at least one AC measurement signal are different.
  • the at least one AC measurement signal is used to offset each other or other AC measurement signals in amplitude within the same cycle; at the same time, the controller also generates at least one driving signal based on the reference voltage, the output voltage of the photovoltaic module and the AC measurement signal.
  • the corresponding connected photovoltaic components of the conversion circuit are controlled to respectively output voltages and currents containing the frequency of the AC measurement signal, and the reference voltage is the photovoltaic power conversion device in the state of supplying power to the power grid. reference input voltage;
  • the controller is also used to synchronize the equivalent impedance measurements of the N photovoltaic modules so that the equivalent impedance measurements are performed simultaneously in the photovoltaic modules.
  • the controller is also used to obtain the corresponding output voltage and output current of the photovoltaic component under the control of the at least one driving signal at the frequency of the AC measurement signal; and is also used to obtain the output voltage and output current corresponding to the frequency of the at least one photovoltaic component according to the The corresponding voltage component and current component at the frequency of the AC measurement signal are used to obtain the equivalent impedance of the photovoltaic module.
  • the controller generating an AC measurement signal includes:
  • the controller is used to generate an AC measurement signal with a specified frequency, a specified amplitude, and a specified phase.
  • the AC measurement signal has the characteristics described in the first and second aspects, so that the generated AC measurement signal is Mutual amplitudes cancel each other in the same cycle;
  • the controller also generates a driving signal based on the reference voltage, the output voltage of the photovoltaic module and the AC measurement signal, including:
  • the controller obtains a second reference voltage based on the superposition of the reference voltage of the corresponding conversion circuit and the corresponding AC measurement signal; then the controller generates a first reference voltage from the second reference voltage and the current output voltage of the corresponding photovoltaic component. modulates a wave, and generates the driving signal according to the first modulated wave.
  • the controller generates a second modulated wave according to the corresponding conversion circuit reference voltage and the current output voltage of the corresponding photovoltaic component; and then the controller superposes the second modulated wave and the corresponding AC measurement signal to obtain a third three modulated waves, and generate the driving signal according to the third modulated wave.
  • the controller further enables the photovoltaic components to perform equivalent impedance measurements at the same time, and the controller has a communication function, for the main measurement in the photovoltaic system Group or main measurement conversion circuit, the controller is used to send the measurement start signal of the main measurement group or main measurement conversion circuit to the slave measurement group or slave measurement conversion circuit of the same photovoltaic system; for the slave measurement group or slave measurement of the photovoltaic system Conversion circuit, the controller is used to obtain the start-up measurement signal issued by the main measurement group or the main measurement conversion circuit in the same photovoltaic system.
  • the transmission protocol of the start-up signal can use wired communication such as PLC communication or wireless communication such as wifi communication. way of communication.
  • the controller further enables the photovoltaic components to perform equivalent impedance measurements at the same time.
  • the controller may not use communication, but use active detection. way to synchronize different photovoltaic power conversion equipment.
  • the controller obtains the voltage fluctuation signal on the grid side of the photovoltaic power conversion equipment from the slave measurement group or the slave measurement conversion circuit in the photovoltaic system; then the controller confirms whether the voltage fluctuation signal contains the main measurement group or the main measurement conversion circuit
  • the equivalent impedance measurement signal corresponds to the frequency fluctuation signal, and finally the controller controls the slave measurement group or the slave measurement conversion circuit to perform equivalent impedance measurement.
  • the controller is used to obtain the equivalent impedance of the photovoltaic component, including: the controller first collects the output voltage of the photovoltaic component under the control of the driving signal and Output current; then, the controller performs frequency domain filtering on the sampled output current and output voltage of the photovoltaic module according to the frequency of the AC measurement signal to obtain the output voltage and output current of the photovoltaic module corresponding to the frequency of the AC measurement signal; finally, the controller Calculate the equivalent impedance of the photovoltaic module based on the output voltage and output current of the photovoltaic module corresponding to the frequency of the AC measurement signal.
  • Figure 1 is a schematic structural diagram of a typical photovoltaic module impedance measurement system provided by the prior art
  • Figure 2 is a schematic diagram of the application scenario of the photovoltaic system provided by this application.
  • FIG. 3 is a schematic structural diagram of the photovoltaic system provided by this application.
  • FIGS. 3-1, 3-2, and 3-3 are schematic diagrams of structural examples of the photovoltaic system provided by this application;
  • FIG. 4 is a schematic structural diagram of the controller of the photovoltaic module provided by this application.
  • FIG. 5 is another structural schematic diagram of the photovoltaic system provided by this application.
  • FIG. 6 is another structural schematic diagram of the photovoltaic system provided by this application.
  • FIG. 7 is another structural schematic diagram of the photovoltaic system provided by this application.
  • FIG. 8 is another structural schematic diagram of the photovoltaic system provided by this application.
  • FIG. 9 is another structural schematic diagram of the photovoltaic system provided by this application.
  • FIG. 10 is another structural schematic diagram of the photovoltaic system provided by this application.
  • Figure 11 is a schematic flow chart of the equivalent impedance measurement method of photovoltaic modules provided by this application.
  • the photovoltaic system provided by this application can be applied to different application scenarios, such as photovoltaic power supply scenarios, photovoltaic hybrid power supply scenarios, etc.
  • the power supply in the photovoltaic power supply scenario, is photovoltaic modules; in the photovoltaic-storage hybrid power supply scenario, the power supply includes photovoltaic modules and energy storage battery strings.
  • the following takes the photovoltaic power supply scenario as an example.
  • the photovoltaic system provided by this application includes N conversion circuits and at least one controller.
  • the N photovoltaic modules are connected to the input terminals of respective conversion circuits.
  • the photovoltaic modules correspond to the conversion circuits one-to-one.
  • the output terminals of the N conversion circuits are connected in series.
  • the first terminal and the second terminal of the N conversion circuits are not connected in series to the busbar.
  • the conversion circuit can be the DC/DC conversion circuit shown in Figure 1
  • the power grid can be the AC power grid shown in Figure 1.
  • the photovoltaic system also includes an inverter.
  • the photovoltaic power conversion devices at the beginning and end are connected to the inverter, and the output end of the inverter is connected to the AC power grid or Household AC electrical equipment.
  • the optional grid can also be a DC grid, for use with DC equipment.
  • the optional conversion circuit in Figure 1 can also be a DC/AC inverter circuit.
  • the output terminals of the N inverter circuits are connected in series.
  • the output terminals of the N inverter circuits do not have the first terminal and the second terminal connected in series with the AC bus. Connection, the AC bus is directly connected to the power grid or household AC electrical equipment.
  • N DC/DC conversion circuits can convert the DC power generated by the photovoltaic modules connected to its input end into DC power with a voltage of a preset value. After the N DC/DC conversion circuits are connected in series, the series The DC power is then output to the inverter circuit.
  • the inverter circuit inverts the DC power output by the N DC/DC conversion circuits into AC power, thereby supplying power to various types of electrical equipment such as AC power grids or AC loads (such as household equipment). .
  • the DC/DC conversion circuit in the photovoltaic system can measure the equivalent impedance of N photovoltaic modules at the same time on the basis of normal power supply to the AC grid or AC load, there is no need to measure the equivalent impedance of the photovoltaic module. Affects the power generation of photovoltaic systems, has strong applicability and high efficiency.
  • FIG 3 is a schematic structural diagram of the photovoltaic system provided by this application.
  • the photovoltaic system includes four photovoltaic modules 10 and four photovoltaic power conversion devices 11.
  • the four photovoltaic modules 10 are respectively connected to the input ends of their respective photovoltaic power conversion devices 11, and the four photovoltaic power conversion devices 11 are connected in series. , the first end and the second end of the four photovoltaic power conversion devices 11 are not connected in series to the busbar.
  • the photovoltaic power conversion equipment 111 includes a conversion circuit 1111 and a controller 1112 respectively.
  • the input end of the conversion circuit 1111 is connected to the input end of the photovoltaic power conversion equipment 111, and the output end of the conversion circuit 1111 is connected to the photovoltaic power conversion equipment.
  • the conversion circuit 1111 is used to convert the output voltage of the photovoltaic module 101 into the output voltage of the photovoltaic power conversion device 111 when supplying power to the grid.
  • the controller 1112 outputs the driving voltage to the conversion circuit 1111.
  • the driving voltage contains the equivalent impedance measurement signal, then collects the voltage and circuit of the photovoltaic module, and outputs the equivalent impedance of the photovoltaic module according to the voltage and circuit of the photovoltaic module.
  • the photovoltaic system performs equivalent impedance measurements on four photovoltaic modules 10 at the same time.
  • the controllers of the four photovoltaic power conversion devices 11 respectively generate four AC measurement signals, and the frequencies of the four AC measurement signals are the same.
  • the initial phases differ by 360 0 /4 in turn, respectively: the phase of the AC measurement signal generated by the controller in the photovoltaic power conversion device 111 is 0 0 , and the phase of the AC measurement signal generated by the controller in the photovoltaic power conversion device 112 is 90 0 , the phase of the AC measurement signal generated by the controller in the photovoltaic power conversion device 113 is 180 0 , and the phase of the AC measurement signal generated by the controller in the photovoltaic power conversion device 114 is 270 0 .
  • the amplitudes of the AC measurement signals of the four photovoltaic modules 10 in the same cycle are superimposed and cancel each other out.
  • the controllers in the four photovoltaic power conversion devices 11 generate four driving signals based on their respective reference voltages and AC measurement signals, and drive The signals control the output voltages of the four photovoltaic modules 10 respectively, where the reference voltage is the reference input voltage of the four photovoltaic power conversion devices 11 respectively when supplying power to the grid.
  • the controllers in the four photovoltaic power conversion devices 11 respectively obtain the output voltages and output currents corresponding to the frequencies of the respective AC measurement signals of the four photovoltaic modules 10 under the control of the driving signals, and then based on the respective AC measurement signals of the four photovoltaic modules 10 Corresponding to the output voltage and output current at the frequency, the equivalent impedances of the four photovoltaic modules 10 are determined simultaneously.
  • FIG. 5 is a schematic structural diagram of the controller of the photovoltaic power conversion equipment provided by this application. As shown in Figure 5, the controller includes a control module 11121, a synchronization module 11122 and an acquisition module 11123.
  • the above control module 11121 generates a driving signal based on the reference voltage V ref1 and the AC measurement signal V ref2 with frequency ⁇ and phase ⁇ . While the control module generates the driving signal, the synchronization module 11122 will notify other photovoltaic power conversion equipment in the photovoltaic system of the start signal. After receiving the start signal, other photovoltaic power conversion equipment in the photovoltaic system will start equivalent impedance measurement at the same time. After the control module generates the driving signal, it outputs the driving signal to the conversion circuit 1111, so that the driving signal controls the output voltage v and output current i of the photovoltaic module 101 through the control conversion circuit 1111 (i.e., the input terminal voltage and input voltage of the photovoltaic power conversion device 111 terminal current).
  • the acquisition module 11123 collects the output voltage and output current of the photovoltaic module 101 within the time interval ⁇ t under the control of the driving signal, and performs the calculation on the output voltage and output current of the photovoltaic module 101 within the time interval ⁇ t according to the frequency ⁇ sent by the control module 11121.
  • Frequency domain filtering is used to obtain the output voltage v( ⁇ ) and output current i( ⁇ ) of the photovoltaic module 101 at frequency ⁇ , and based on the output voltage v( ⁇ ) and output current i( ⁇ ) of the photovoltaic module 101 at frequency ⁇ , The equivalent impedance Z( ⁇ ) of the photovoltaic module 101 is determined.
  • FIG. 6 is another structural schematic diagram of the controller of the photovoltaic power conversion device provided by the present application.
  • the control module 11121 includes a control unit 111211 and a measurement signal generation unit 111212.
  • the acquisition module 11123 includes a sampling unit 111231 and a filtering unit 111232.
  • the controller also includes a determination unit 111233.
  • the synchronization module 11122 is used for each photovoltaic power conversion device. synchronization between.
  • Each photovoltaic power conversion device determines the reference voltage V ref1 according to the current working status of itself and the photovoltaic components connected to it, and converts the reference signal V to ref1 is sent to the respective control units of the photovoltaic power conversion equipment.
  • each photovoltaic power conversion device when the four photovoltaic power conversion devices 11 in the photovoltaic system are in the non-power-limited working state, each photovoltaic power conversion device performs maximum power point tracking (MPPT) to maximize the output power; the four photovoltaic power conversion devices in the photovoltaic system When the photovoltaic power conversion equipment is in a power-limited working state, each photovoltaic power conversion equipment actively limits the output power.
  • the reference voltage V ref1 is the reference input voltage of each photovoltaic power conversion device when supplying power to the grid. In other words, during the entire measurement period of the equivalent impedance of each photovoltaic module, the average value of the output voltage of each photovoltaic module can be maintained Equal to V ref1 , the normal power generation operation of the photovoltaic system is maintained.
  • the measurement signal generation unit 111212 in the photovoltaic power conversion device 111 When the photovoltaic system starts to measure the equivalent impedance of all photovoltaic modules in the system simultaneously, the measurement signal generation unit 111212 in the photovoltaic power conversion device 111 generates the AC measurement signal V ref2 according to the set frequency ⁇ , phase ⁇ and amplitude A. At the same time, the synchronization module 11122 transmits the signal that the photovoltaic power conversion device 111 starts measuring equivalent impedance to the photovoltaic power conversion device 112, the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 in the photovoltaic system.
  • the photovoltaic power conversion device 112 After the respective synchronization modules in the photovoltaic power conversion equipment 113 and the photovoltaic power conversion equipment 114 detect the start signal sent by the photovoltaic power conversion equipment 111, they simultaneously start measuring the equivalent impedance of the respective connected photovoltaic components. Specifically, the photovoltaic power conversion device 112 performs equivalent impedance measurement on the photovoltaic component 102, the photovoltaic power conversion device 113 performs the equivalent impedance measurement on the photovoltaic component 103, and the photovoltaic power conversion device 114 performs the equivalent impedance measurement on the photovoltaic component 104.
  • the respective measurement signal generating units in the photovoltaic power conversion device 112, the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 generate respective AC measurement signals according to the set frequency ⁇ , phase ⁇ and amplitude A.
  • the AC measurement signals generated by each of the four measurement signal generating units have the same frequency ⁇ , the same amplitude A, and different phases ⁇ , and the phases differ by 360 0 /4 in turn.
  • phase of the AC measurement signal generated by the measurement signal generation unit 111212 as the reference that is, the phase of the AC measurement signal generated by the measurement signal generation unit 111212 as the reference is 0 0
  • the photovoltaic power conversion device 112 the photovoltaic power conversion device 113 and the photovoltaic power
  • the phases of the AC measurement signals generated in the conversion devices 114 are respectively 90 0 , 180 0 , and 270 0 .
  • the AC measurement signals generated by each of the four measurement signal generation units are superimposed and offset each other in the same cycle, which means that the equivalent impedance of their respective photovoltaic modules can be measured without causing power fluctuations in the photovoltaic system.
  • the respective measurement signal generation units in the four photovoltaic power conversion devices After the respective measurement signal generation units in the four photovoltaic power conversion devices generate AC measurement signals, the respective AC measurement signals are input to the control unit.
  • the AC measurement signal V ref2 is sent to the control unit 111211, and the control unit generates a driving signal based on the reference signal V ref1 , the AC measurement signal V ref2 and the output voltage V pv of the photovoltaic module 101 at that time.
  • the photovoltaic module output voltage V pv is collected by the sampling unit 111231 of the photovoltaic power conversion device 111 within the time interval ⁇ t of the photovoltaic module 101, and the collected output voltage V pv is output to the control unit 111211.
  • control unit 111211 After the control unit 111211 generates the drive signal, the control unit 111211 outputs the drive signal to the conversion circuit 1111 of the photovoltaic power conversion device 111.
  • Other control units in the photovoltaic system also output their respective drive signals to their corresponding conversion circuits.
  • the driving signal is used to control the switching state of the semiconductor switching device in the conversion circuit 1111, thereby generating voltage and current including corresponding AC signals at the port of the photovoltaic module 101, while maintaining the average output voltage of the photovoltaic module 101 equal to the reference voltage V ref1 .
  • the respective AC measurement signals of the four photovoltaic power conversion devices are generated by a signal generation unit in a controller.
  • the signal generation unit 111212 in the controller 1112 generates four different AC measurement signals at the same time, and then generates them respectively.
  • Four different AC measurement signals are input into the control unit, and finally four drive signals are generated to control four photovoltaic power conversion devices.
  • This method of control is more centralized, does not require additional synchronization equipment, and is conducive to system simplification.
  • the photovoltaic power conversion device 111 includes a conversion circuit 1111 and a photovoltaic impedance detection unit 1112.
  • the conversion circuit 1111 is a DC/DC conversion circuit.
  • the DC/DC conversion circuit includes a Boost circuit.
  • the Boost circuit includes a first inductor and a first switch tube. .
  • the positive input terminal of the Boost circuit is connected to the negative output terminal of the Boost circuit through the first inductor and the first switch tube.
  • the photovoltaic power conversion device controls the conduction time of the first switch tube according to the driving signal, thereby controlling the output voltage of the photovoltaic module.
  • the conversion circuit 1111 may also be an inverter, which includes an inverter circuit that includes a first phase bridge arm, a second phase bridge arm, and a third phase bridge arm.
  • the first phase bridge arm, the second phase bridge arm and the third phase bridge arm are all connected in parallel to the input end of the inverter circuit, and the driving signal includes a first driving sub-signal, a second driving sub-signal and a third driving sub-signal.
  • the photovoltaic power conversion equipment controls the conduction time of the switch tube of the first phase bridge arm and the conduction time of the switch tube of the second phase bridge arm according to the first drive sub-signal, the second drive sub-signal and the third drive sub-signal respectively. and the conduction time of the switch tube of the third phase bridge arm, thereby controlling the output voltage of the photovoltaic module.
  • the output voltage and output current of the four photovoltaic modules contain the information of the AC measurement signal.
  • Each of the four photovoltaic power conversion equipment in the photovoltaic power generation system collects the voltage and current within the time interval ⁇ t of the respective corresponding photovoltaic modules.
  • its acquisition unit 111231 is used to collect the voltage V pv and current I pv of the photovoltaic module 101 within the time interval ⁇ t. Then the acquisition unit 111231 outputs the collected voltage and current of the photovoltaic module 101 to the filter unit 111232.
  • the filtering units of other photovoltaic power conversion equipment in the photovoltaic system, the photovoltaic power conversion equipment 102, the photovoltaic power conversion equipment 103 and the photovoltaic power conversion equipment 104 also filter the output voltage and output current of their respective photovoltaic components, and then obtain the respective For the output voltage and output current at frequency ⁇ , finally, the equivalent impedance of each photovoltaic module is obtained based on the filtered output voltage and output voltage.
  • the synchronization module in the photovoltaic power conversion equipment is used to synchronize the photovoltaic power conversion equipment in the photovoltaic system, so that the photovoltaic power conversion equipment starts to measure the equivalent impedance of the respective connected photovoltaic modules at the same time.
  • the synchronization module can send signals to other photovoltaic power conversion devices in the photovoltaic system in a wired or wireless manner.
  • wired communication PLC communication can be used. PLC communication can use the existing power lines connected between photovoltaic power conversion equipment to communicate without deploying additional physical communication lines.
  • the synchronization module loads the start signal onto the power line between the photovoltaic power conversion equipment, and sends the start signal to other photovoltaic power conversion equipment connected to it.
  • each photovoltaic power conversion After the synchronization module in the other photovoltaic power conversion equipment receives the start signal, each photovoltaic power conversion The device simultaneously starts measuring the equivalent impedance of the photovoltaic modules connected to it.
  • wired communication can also use other technologies, such as Ethernet, etc., which are not limited here.
  • wireless communication methods the deployment of physical communication lines can be avoided and the maintenance costs of photovoltaic systems can be reduced.
  • multiple communication methods such as wifi, 5G, and Bluetooth can be used, and there are no restrictions here.
  • the synchronization module in the photovoltaic power conversion equipment does not need to use a communication module.
  • the function of the synchronization module is to enable all photovoltaic power conversion equipment in the photovoltaic system to measure the equivalent impedance of the photovoltaic modules connected to them at the same time.
  • a driving signal containing an AC measurement signal will be loaded into the photovoltaic power conversion device 111.
  • This AC measurement signal will cause the entire photovoltaic
  • the system is slightly jittering. This jitter contains the frequency component of the AC measurement signal with the frequency ⁇ .
  • the synchronization modules in other photovoltaic power conversion equipment in the photovoltaic system detect this fluctuation and detect that the fluctuation contains the frequency component with the frequency ⁇ .
  • the signal component confirms that the photovoltaic power conversion device 111 starts the photovoltaic equivalent impedance measurement. Then the photovoltaic power conversion devices each start photovoltaic equivalent impedance measurement.
  • each controller in the photovoltaic system starts measuring the equivalent impedance of the photovoltaic modules in sequence, and the phase setting of each AC measurement signal is based on the fact that all controllers in the photovoltaic system start measuring at the same time, therefore
  • the actual AC measurement signal phase is set according to the phase set under the premise of starting the measurement at the same time, it will inevitably occur that the amplitude superposition of all AC measurement signals in the photovoltaic system is not zero in the same period. situation.
  • the time delay difference for each photovoltaic power conversion device to start measuring the equivalent impedance of the photovoltaic module can be reasonably obtained.
  • the frequency of the AC measurement signal is known, so The phase difference between the actual AC measurement signal and the theoretical AC measurement signal can be deduced based on the delay difference and frequency. Compensating the phase will make it possible to obtain the AC measurement signal corresponding to the slave measurement group and the master measurement group or the third AC measurement signal.
  • the AC measurement signals generated by the measurement signal generation units in each photovoltaic power conversion equipment have the same frequency and the same amplitude, and the phase difference is 360 0 /N, where N is the number of photovoltaic modules in the photovoltaic system, and the difference between different photovoltaic modules is The carried AC measurement signals cancel each other out within the same period. Therefore, when the photovoltaic system measures the equivalent impedance of multiple photovoltaic modules in the system, it will not cause power fluctuations in the photovoltaic system, ensuring the continuous and stable operation of the photovoltaic system.
  • the photovoltaic system measures the equivalent impedance of four photovoltaic modules 10 at the same time.
  • the photovoltaic system divides the four photovoltaic modules into two groups. As shown in Figure 7, photovoltaic module 101 and photovoltaic power conversion equipment 111, photovoltaic module 102 and photovoltaic power conversion equipment 112 are the first group, photovoltaic module 103 and photovoltaic power conversion equipment 113, photovoltaic module 104 and photovoltaic power conversion equipment 114 are Second Group. After grouping, the respective measurement signal generation units in the photovoltaic power conversion equipment of the first group and the second group respectively generate AC measurement signals according to the set frequency ⁇ , phase ⁇ and amplitude A.
  • the frequency ⁇ and amplitude A of the AC measurement signals generated by the first group and the second group are the same within the group and between the groups, while the phase ⁇ is the same within the group but different between the groups.
  • the difference between the groups is 360 0 /2.
  • 2 is the number of groups divided into photovoltaic modules in the entire photovoltaic system, based on the phase of the AC measurement signal generated in the first group, that is, in the first group, the photovoltaic power conversion equipment 111 and the photovoltaic power conversion equipment 112
  • the phase of the AC measurement signal generated by each is 0 0
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 is 180 0 .
  • the AC measurement signals generated by each of the four measurement signal generation units are superimposed and offset each other in the same cycle, which can measure the equivalent impedance of their respective photovoltaic modules without causing power fluctuations in the photovoltaic system.
  • this embodiment also requires a synchronization module.
  • one group is the master measurement group, and the rest are slave measurement groups.
  • the first group is the master measurement group
  • the second group is the slave measurement group.
  • the main measurement group first starts the equivalent impedance measurement of the photovoltaic module 101 and the photovoltaic module 102 in the group. After the respective measurement signal generation units in the photovoltaic power conversion equipment 111 and the photovoltaic power conversion equipment 112 respectively generate AC measurement signals, the photovoltaic power conversion equipment 111 and photovoltaic power conversion equipment 112 send the starting equivalent impedance measurement signal of the first group to the secondary measurement group, that is, the second group.
  • the second group After receiving the starting equivalent impedance measurement signal of the first group, the second group starts to measure the second
  • the photovoltaic modules 103 and 104 in the group perform equivalent impedance measurements.
  • AC measurement signals are respectively generated from the respective measurement signal generation units in the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 in the measurement group.
  • the respective AC measurement signals are input to the control unit.
  • the AC measurement signal V ref2 is sent to the control unit 111211.
  • the control unit determines the output voltage V of the photovoltaic module 101 based on the reference signal V ref1 , the AC measurement signal V ref2 and the current output voltage V of the photovoltaic module 101 . pv generates driving signals.
  • the photovoltaic module output voltage V pv is collected by the sampling unit 111231 of the photovoltaic power conversion device 111 within the time interval ⁇ t of the photovoltaic module 101, and the collected output voltage V pv is output to the control unit 111211. After the control unit 111211 generates the drive signal, the control unit 111211 outputs the drive signal to the conversion circuit 1111 of the photovoltaic power conversion device 111. Other control units in the photovoltaic system also output their respective drive signals to their corresponding conversion circuits.
  • the driving signal is used to control the switching state of the semiconductor switching device in the conversion circuit 1111, thereby generating voltage and current including corresponding AC signals at the port of the photovoltaic module 101, while maintaining the average output voltage of the photovoltaic module 101 equal to the reference voltage V ref1 .
  • the output voltage and output current of the four photovoltaic modules contain the information of the AC measurement signal.
  • Each of the four photovoltaic power conversion equipment in the photovoltaic power generation system collects the voltage and current within the time interval ⁇ t of the respective corresponding photovoltaic modules.
  • its acquisition unit 111231 is used to collect the voltage V pv and current I pv of the photovoltaic module 101 within the time interval ⁇ t. Then the acquisition unit 111231 outputs the collected voltage and current of the photovoltaic module 101 to the filter unit 111232.
  • the respective filtering units of the first group of photovoltaic power conversion equipment 102, the second group of photovoltaic power conversion equipment 103 and the photovoltaic power conversion equipment 104 also control the output voltage and output of their respective photovoltaic modules.
  • the current is filtered, and then the output voltage and output current at frequency ⁇ are obtained respectively.
  • the equivalent impedance of the respective photovoltaic modules is obtained based on the filtered output voltage and output voltage.
  • the AC measurement signal generated by the measurement signal generation unit in each photovoltaic power conversion device in the photovoltaic system of this embodiment has the same frequency ⁇ and the same amplitude ⁇ within the group as between the groups, and the phase ⁇ is the same within the group but different between groups, and the phases between groups are sequentially
  • the difference is 360 0 /M, where M is the number of groups that group photovoltaic modules in the photovoltaic system.
  • the AC measurement signals between different groups cancel each other out in the same cycle, and M between different groups is the same.
  • the photovoltaic system measures the equivalent impedance of six photovoltaic modules 10 at the same time.
  • the photovoltaic system divides the six photovoltaic modules into two groups. As shown in Figure 8, photovoltaic module 101 and photovoltaic power conversion equipment 111, photovoltaic module 102 and photovoltaic power conversion equipment 112, photovoltaic module 103 and photovoltaic power conversion equipment 113 are the first group, photovoltaic module 104 and photovoltaic power conversion equipment 114, The photovoltaic module 105 and the photovoltaic power conversion device 115, the photovoltaic module 106 and the photovoltaic power conversion device 116 are the second group, that is, each group includes three photovoltaic modules.
  • the groups can also be divided unequally.
  • the first group includes two photovoltaic modules, that is, the photovoltaic module 101 and the photovoltaic power conversion device 111, and the photovoltaic module 102 and the photovoltaic power conversion device 112 are the first group;
  • the second group includes four Photovoltaic modules, namely photovoltaic module 103 and photovoltaic power conversion device 113, photovoltaic module 104 and photovoltaic power conversion device 114, photovoltaic module 105 and photovoltaic power conversion device 115, photovoltaic module 106 and photovoltaic power conversion device 116 are the second group.
  • the respective measurement signal generation units in the photovoltaic power conversion equipment of the first group and the second group respectively generate AC measurement signals according to the set frequency ⁇ , phase ⁇ and amplitude A.
  • the AC measurement signal amplitude A generated by the first group and the second group is the same within the group, and is the same or different between the groups.
  • the amplitude of the first group is A 1
  • the amplitude of the second group is A 2
  • the frequency ⁇ is the same within the group, but different or the same between groups.
  • the frequency of the first group is ⁇ 1
  • the frequency of the second group is A 2
  • the frequency is ⁇ 2
  • the phase ⁇ is different within the group, and the difference within the group is 360 0 /3. 3 is the number of photovoltaic modules in the group.
  • the phases between groups are the same or different.
  • the first group based on the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 111 in the first group, that is, the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 111 in the first group is 0 0 , the first group
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 112 in the first group is 120 0
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 113 in the first group is 240 0
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 113 in the second group is
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 113 in the second group is
  • the phase of the AC measurement signal generated by the power conversion device 114 is the reference, that is, the phase of the AC measurement signal generated by the second group of photovoltaic power conversion devices 114 is 0 0
  • the phase of the AC measurement signal generated by the photovoltaic power conversion device 115 in the first group is
  • the first group and the second group are not evenly divided.
  • the AC measurement signal amplitude A generated by the first group and the second group is in the group.
  • the amplitude of the first group is A 1
  • the amplitude of the second group is A 2
  • the frequency ⁇ is the same within the group, but different or the same between the groups, specifically, the first The frequency of the group is ⁇ 1 and the frequency of the second group is ⁇ 2
  • the phase ⁇ is different within the group.
  • the AC measurement signals within the group in the first group differ by 360 0 /2 in sequence, and the AC measurement signals within the group in the second group differ in sequence
  • the difference is 360 0 /4.
  • the divisors 2 and 4 are the number of photovoltaic modules in the group.
  • the phases between groups are the same or different.
  • the first group based on the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 111 in the first group, that is, the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 111 in the first group is 0 0 , the first group In the second group, the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 112 is 180 0 ; in the second group, the phase of the AC measurement signal generated by the photovoltaic power conversion equipment 113 in the second group is used as the benchmark, that is, the photovoltaic power of the first group The phase of the AC measurement signal generated by the conversion device 113 is 0 0 , the phase of the AC measurement signal generated by the photovoltaic power conversion device 114 in the second group is 90 0 ; the phase of the AC measurement signal generated by the photovoltaic power conversion device 115 in the second group The phase of the signal is 180 0 , and the phase of the AC measurement signal generated by the photovoltaic power conversion device 116 in the second group is a
  • each photovoltaic power conversion device After each group of photovoltaic power conversion devices in the photovoltaic system generates AC measurement signals, equivalent impedance measurements are performed on the corresponding photovoltaic modules. The subsequent steps are consistent with the previous embodiments and will not be described in detail. It should be pointed out that when determining the unit, the filter unit in each photovoltaic power conversion device filters the output voltage and output current of the corresponding photovoltaic module collected by the acquisition unit, and needs to filter according to the frequency ⁇ of the corresponding AC measurement signal. .
  • each filtering unit in the first group filters the output voltage V pv and the output current I pv of the corresponding photovoltaic module to obtain the output voltage V pv and the output current I pv at the frequency ⁇ 1
  • each filter unit in the second group filters the output voltage V pv and the output current I pv of the corresponding photovoltaic module to obtain the output voltage V pv ( ⁇ 1 ) and the output current I pv at the frequency ⁇ 2
  • the AC measurement signals generated by the measurement signal generation units in each photovoltaic power conversion equipment in the photovoltaic system have the same frequency and the same amplitude within the group.
  • the phases of each AC measurement signal in the group differ by 360 0 /Z, where Z is the number of photovoltaic modules in the group, so the AC measurement signals in the group cancel each other out in the same cycle.
  • Z can be different between different groups, and the frequency ⁇ and amplitude A between different groups can be the same or different.
  • the photovoltaic system measures the equivalent impedance of four photovoltaic modules 10 at the same time.
  • the photovoltaic system divides the four photovoltaic modules into two groups. As shown in Figure 9, the first group contains one photovoltaic module and the second group contains three photovoltaic modules.
  • the photovoltaic module 101 and the photovoltaic power conversion device 111 are the first group; the photovoltaic module 102 and the photovoltaic power conversion device 112, the photovoltaic module 103 and the photovoltaic power conversion device 113, the photovoltaic module 104 and the photovoltaic power conversion device 114 are the second group. , that is, each group contains 3 photovoltaic modules.
  • the respective measurement signal generation units in the photovoltaic power conversion equipment of the first group and the second group respectively generate AC measurement signals according to the set frequency ⁇ , phase ⁇ and amplitude A.
  • the frequency ⁇ of the AC measurement signal generated by the first group and the second group is the same within the group and between the groups; the amplitude A is the same within the group but different between the groups.
  • the amplitude of the AC measurement signal of the first group A is A 1
  • the amplitude A of the AC measurement signal generated by the first group of photovoltaic power conversion devices 111 is A 1
  • the amplitude A of the second group of photovoltaic power conversion devices 112 is A 1
  • the amplitude A of the AC measurement signal generated by the photovoltaic power conversion device 113 is A 2
  • the amplitude A of the AC measurement signal generated by the photovoltaic power conversion device 113 is A 3
  • the phase ⁇ is the same within the group, and the difference between the groups is 360 0 /2.
  • 2 is the number of groups that the photovoltaic system groups the photovoltaic modules in the system. Specifically, based on the phase of the AC measurement signal generated in the first group, that is, the phase of the AC measurement signal generated by the photovoltaic power conversion device 111 in the first group is 0 0 , then in the second group, the photovoltaic power conversion The phase of the AC measurement signal generated by each of the device 112, the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 is 180 0 .
  • the frequency of the AC measurement signal generated by the measurement signal generating unit in each photovoltaic power conversion device in the photovoltaic system is the same between groups and within the group; in terms of amplitude A, the amplitude A of different AC measurement signals within the group It can be different.
  • the sum of the amplitude A of each AC measurement signal in different groups is equal between groups; in terms of phase ⁇ , the phases of the AC measurement signals between different groups differ by 360 0 /M, where M is the photovoltaic system.
  • M is the photovoltaic system.
  • the number of groups of photovoltaic modules in the system ensures that the AC measurement signals of different groups cancel each other out in the same cycle. Therefore, when the photovoltaic system measures the equivalent impedance of multiple photovoltaic modules in the system, it will not cause power fluctuations in the photovoltaic system, ensuring the continuous and stable operation of the photovoltaic system.
  • the photovoltaic system can group the photovoltaic components in the system differently, and then, based on the grouping situation, generate specific AC measurement signals and specific photovoltaic power conversion on the premise that different AC measurement signals cancel each other out in the same cycle.
  • the AC signals generated by the equipment can have different amplitudes, phases, and frequencies. This ensures that the AC measurement signal will not cause jitter in the output power of the photovoltaic system, ensures that the photovoltaic system will not cause its working status while measuring the impedance of multiple photovoltaic modules, and ensures that its output frequency will not fluctuate greatly, improving efficiency.
  • the measurement signal generation unit in the photovoltaic power conversion device in the photovoltaic system generates AC measurement signals of at least two different frequencies at the same time, and can simultaneously obtain at least two equal measurements of the photovoltaic components at different frequencies. effective impedance to improve efficiency.
  • the measurement signal generation unit 111212 in the photovoltaic power conversion device 111 performs the equivalent impedance measurement according to the set frequency ⁇ ( ⁇ 1 , ⁇ 2 ), The phase ⁇ and the amplitude A generate an AC measurement signal V ref2 ( ⁇ 1 , ⁇ 2 ), which contains two frequencies ( ⁇ 1 , ⁇ 2 ). Based on the synchronization module in the photovoltaic system, other photovoltaic power conversion devices in the photovoltaic system simultaneously measure the equivalent impedance of their respective connected photovoltaic modules.
  • the respective measurement signal generating units in the photovoltaic power conversion device 112, the photovoltaic power conversion device 113 and the photovoltaic power conversion device 114 generate respective measurement signals according to the set frequency ⁇ ( ⁇ 1 , ⁇ 2 ), phase ⁇ and amplitude A.
  • AC measurement signals each AC measurement signal contains two frequencies, a first frequency and a second frequency ( ⁇ 1 , ⁇ 2 ).
  • the AC measurement signals generated by each of the four measurement signal generating units include the first frequency ⁇ 1 and the second frequency ⁇ 2 , and ⁇ 1 and ⁇ 2 are different.
  • the respective frequency ⁇ 1 is the same as the amplitude A
  • the phase ⁇ is different
  • the phases are sequentially different by 360 0 /4.
  • phase of the AC measurement signal of the first frequency ⁇ 1 component generated by the measurement signal generation unit 111212 is 0 0
  • the photovoltaic power is respectively 90 0 , 180 0 and 270 0 .
  • the phases of the AC measurement signals of the second frequency ⁇ 2 component generated by the four measurement signal generation units are 90 0 , 180 0 and 270 0 respectively.
  • the photovoltaic system can measure the equivalent impedance of their respective photovoltaic modules without causing power fluctuations in the photovoltaic system. It has system stability and can obtain photovoltaic Equivalent impedance of components at multiple different frequencies to improve measurement efficiency.
  • the AC measurement signal generated by the measurement signal generation unit 111212 in the photovoltaic power conversion device 111 includes at least two different frequencies and also includes a third frequency ⁇ 3 ,..., an nth frequency ⁇ n , where n is greater than 1. integer.
  • the determining unit 111233 in the photovoltaic power conversion device 111 determines the photovoltaic module 101 at the second frequency according to the output voltage V pv ( ⁇ 1 ) and the output current I pv ( ⁇ 1 ) of the photovoltaic module 101 at the first frequency ⁇ 1 .
  • the photovoltaic module 102, the photovoltaic module 103 and the photovoltaic module 104 can also obtain equivalent impedances at different frequencies at the same time.
  • the control unit in each photovoltaic power conversion device generates a driving signal based on its respective reference voltage, AC measurement signal and current voltage of the corresponding photovoltaic module, wherein the AC measurement signal of the photovoltaic module each contains at least two different frequencies, at least two different frequencies Including a first frequency and a second frequency;
  • the acquisition unit in each photovoltaic power conversion device obtains the output voltage and output current of the photovoltaic component under the control of the corresponding driving signal, and the output voltage and output current of the photovoltaic component include the first frequency component and the second frequency component, and then each filtering unit filters the output voltage and output current of the photovoltaic module according to the first frequency and the second frequency, and obtains the output voltage and output current of the photovoltaic module analyzed at the first frequency and the photovoltaic The output voltage and output current of the component at the second frequency; the photovoltaic power conversion device determines the photovoltaic power conversion device based on the output voltage and output current of each photovoltaic component at the first frequency
  • the above embodiments in this application all set the frequency, phase, and amplitude of each AC measurement signal with the goal that the amplitudes of different AC measurement signals in the photovoltaic system are superimposed and offset to zero within the same period.
  • the frequency, phase and phase of each AC measurement signal can be set according to the goal that the amplitude superposition of the different AC measurement signals in the same period is less than the set threshold. amplitude.
  • the frequency, amplitude and phase of the AC measurement signal can be set more flexibly, making the photovoltaic system more flexible and adaptable.
  • this embodiment can also be combined with the previous embodiment.
  • different values can be obtained by designing the frequency, phase, and amplitude. A combination of AC measurement signals.
  • Figure 11 is a schematic flow chart of the equivalent impedance measurement method of multi-machine photovoltaic modules provided by this application.
  • the equivalent impedance measurement method of multi-machine photovoltaic modules provided by the embodiment of the present application is suitable for the photovoltaic system shown in Figures 5 to 10 that supports equivalent impedance measurement of multi-machine photovoltaic modules.
  • the equivalent impedance measurement method of multi-machine photovoltaic modules may include the following steps:
  • N AC measurement signals are generated, and the amplitudes of the N AC measurement signals in the same cycle cancel each other out.
  • the N AC measurement signals are superimposed on each other to obtain a superimposed signal, and the amplitude of the superimposed signal is less than or equal to the set threshold.
  • the amplitude of the superimposed signal is less than or equal to the set threshold, the superimposed signal will not Affecting the normal operation of the photovoltaic system, the impact of the superimposed signal on the photovoltaic system will not exceed the tolerance range of the photovoltaic system.
  • a phase shift method can be used to generate N AC measurement signals, and the phases of the N AC measurement signals are different.
  • a feasible implementation method is that the frequency and amplitude of the N AC measurement signals are consistent, and the N AC measurement signals have different phases.
  • the phase difference between any two adjacent AC measurement signals of N AC measurement signals is 360 0 /N.
  • the second reference voltage is obtained by superposing the reference voltage of each conversion circuit and the corresponding AC measurement signal; then the first modulation wave is generated according to the second reference voltage and the current output voltage of the corresponding photovoltaic component, and according to The first modulated wave generates the driving signal, and the control signal is used to control the correspondingly connected photovoltaic modules of the N conversion circuits to respectively output voltages and currents containing the frequency of the AC measurement signal;
  • the drive signal is generated according to the third modulated wave, and the control signal is used to control the correspondingly connected photovoltaic modules of the N conversion circuits to respectively output voltages and currents containing the frequency of the AC measurement signal.
  • S3 obtain the output voltage and output current of N photovoltaic modules controlled by driving voltage.
  • the conversion circuit is controlled according to N driving voltages.
  • the driving voltage can be used to control the on and off of the switching tube of the conversion circuit.
  • the conversion circuit can convert the output voltage of the photovoltaic module, and the output power of the photovoltaic module is constant. By controlling the output voltage of the photovoltaic module, the output current of the photovoltaic module can be controlled. Since the driving voltage is The AC measurement signal is included, so the output voltage and output current of the photovoltaic module also include the frequency component of the AC measurement signal.
  • the output voltage and output current include the frequency component of the AC measurement signal, and output the N photovoltaic modules according to the frequency of the AC measurement signal.
  • the voltage and output current are filtered to obtain the output voltage and output current at the frequency corresponding to the AC measurement signal.
  • the N photovoltaic cells are obtained by comparing the output voltage and output current at the frequency corresponding to the AC measurement signal. The equivalent impedance of the component.
  • the AC measurement signals generated in the group of this embodiment each contain at least two different frequencies ⁇ ( ⁇ 1 , ⁇ 2 ); the amplitudes A of the AC measurement signals of different frequency components are the same, and the phases ⁇ differ in turn by 360 0 /N, where N is the number of AC measurement signals with frequency components. Therefore, the signals of AC measurement signals with different frequency components cancel each other out in the same cycle.
  • the AC measurement signals with different frequency components generated in the entire photovoltaic system are the same in the same cycle. Superpositions cancel each other out. Therefore, when the photovoltaic system measures the equivalent impedance of multiple photovoltaic modules in the system, it will not cause power fluctuations in the photovoltaic system, ensuring the continuous and stable operation of the photovoltaic system. At the same time, the equivalent impedance of photovoltaic modules at multiple different frequencies can be obtained at one time to improve measurement efficiency.

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Abstract

本申请提供了一种多机光伏组件的等效阻抗测量的光伏系统、方法及光伏功率变换设备。其中，光伏组件通过光伏功率变换设备连接电网。所述光伏系统同时对N（N大于等于2）个光伏组件进行同步移相阻抗检测，生成N个光伏组件的交流测量信号，所述N个光伏组件的交流测量信号在一个周期内的振幅叠加相互抵消，将N个光伏组件的交流测量信号加载到各自的光伏功率变换设备中，进而获取N个光伏组件在各自交流测量信号对应频率下的输出电压和输出电流，从而同时确定N个光伏组件的等效阻抗，所述N个光伏组件的交流测量信号的相互叠加不会引起所述光伏系统的输出功率出现超过阈值范围的波动，可以在光伏系统运行的过程中，同时检测所述光伏系统中的多个光伏组件的等效阻抗，提高测量效率，适应性强。

Description

一种多机光伏组件的等效阻抗测量的光伏系统、方法及光伏功率变换设备 技术领域
本申请涉及光伏领域，一种多机光伏组件的等效阻抗测量的光伏系统、方法及光伏功率变换设备。
背景技术
近年来，光伏装机量不断攀升，逐步成为主流发电技术。保证光伏系统长期可靠运行是行业关注的重点，因此光伏组件的健康状态检测尤为重要。
目前，在学术研究中根据等效电路的方法来分析光伏组件健康状态的方法，通过测量获取光伏组件等效电路参数，根据测量得到的参数来判断光伏组件的健康状况，该方法可以全面的反向光伏组件的健康状况。现有的光伏组件阻抗测量方法，主要是离线式的光伏组件阻抗测量方法，该方法在进行等效阻抗测量时光伏组件与逆变器断开，会影响光伏系统的总体发电量，如图1所示，在测量光伏组件的等效阻抗时，将连接变换电路的光伏组件断开后连接至阻抗分析仪，此时光伏系统停止向电网发电，通过阻抗分析仪计算下的光伏组件等效阻抗。
由于离线是光伏阻抗测量方法，影响发电量，因此业界提出了在线式的光伏阻抗测量方法，即将阻抗测量功能与变换电路集成在一起，即可以完成光伏组件的阻抗测量，也不用断开与电网的连接影响发电量。但是，在线式阻抗测量方法最大的缺点是产生较大的功率波动，严重影响发电量以及并网稳定。
发明内容
本申请提供了一种光伏组件的等效阻抗测量方法、光伏系统及光伏功率变换设备，可同时对多个光伏组件进行等效阻抗测量，且不会引起光伏系统的功率波动，进而不影响光伏系统的正常发电，适用性强。
第一方面，本申请提供了一种光伏组件的等效阻抗测量方法，光伏组件通过变换电路连接电网。该方法包括：同时对N(N大于等于2的整数)个光伏组件进行同步移相阻抗测量，所述每个光伏组件的输出端连接对应变换电路输入端，所述N个变换电路的输出端串联，所述每个变换电路都连接到控制器，当光伏组件平均输出电压保持在一定范围内时，即所述的光伏系统的光伏组件处于正常工作状态，其输出电压维持正常的波动，且波动范围在光伏系统设置的阈值范围之内，不会一起光伏系统的正常运行，在该中状态下所述光伏系统生成N个光伏组件的交流测量信号，所述N个光伏组件的交流测量信号在一个周期内的振幅叠加相互抵消；将N个光伏组件的交流测量信号加载到各自的变换电路中，进而获取N个光伏组件在各自交流测量信号对应频率下的输出电压和输出电流，从而同时确定N个光伏组件的等效阻抗。所述方法可在向电网正常供电的基础上，通过将在同一个周期信号内振幅叠加相互抵消的交流测量信号分别加载到在N个变换电路中，使得每个变换电路对应相连的光伏组件的输出电压和输出电流包含有对应交流测量信号的频率分量，进而根据所述对应交流测量信号的频率分量确定对应光伏组件的等效阻抗。本申请中的方法在完成对N个光伏组件的等效阻抗的测量的同时不会引起光伏系统的功率波动，进而不影响光伏系统的正常发电， 适用性强。
结合第一方面，在第一种可能是实施方式中，生成N个光伏组件的交流测量信号，所述N个光伏组件的交流测量信号的频率一致，为第一频率；同时这N个光伏组件的交流测量信号的相位不同，N个光伏组件的交流测量信号中任意相邻两个交流测量信号的相位依次相差360 0/N；可以理解的，生成N个频率相同、相位依次相差360 0/N的交流测量信号，这N个交流测量信号在同一个周期中振幅叠加相互抵消，因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第一方面，在第二种可能的实施方式中，生成N个光伏组件的交流测量信号。首先，将N个光伏组件的交流测量信号分为M组，M大于等于2小于N的整数；M组光伏组件的交流测量信号，在频率上，组内与组间的频率一致，为第一频率；在振幅上，组内与组间的振幅一致，为第一振幅；在相位上，组内的初始相位一致，组间的初始相位不同，任意相邻两组交流测量信号的相位依次相差360 0/M。可以理解的，将N个光伏组件的交流测量信号光伏功率变换设备分为M组，M组光伏组件的交流测量信号频率相同、相位组间依次相差360 0/M，在组与组之间的交流测量信号叠加中，振幅相互抵消，因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第一方面，在第三种可能的实施方式中，生成N个光伏组件的交流测量信号。首先，所述N个光伏组件的交流测量信号分为M组，M大于等于2小于N的整数，每组包含Z个交流测量信号，Z为大于等于1的整数，每组中Z的个数可以不等；M组光伏组件的交流测量信号，在频率上，各组内的频率相同，各组间的频率相同或不同；在相位上，各组内的初始相位不同，在组内任意相邻两个交流测量信号的相位依次相差360 0/Z。可以理解的，将N个光伏功率变换设备分为M组，在每个M组内，光伏组件的交流测量信号频率相同、相位依次相差360 0/Z。在组内的交流测量信号叠加中，振幅相互抵消，从而在M个组间的交流信号叠加中，振幅同样相互抵消。因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第一方面，在第四种可能的实施方式中，生成N个光伏组件的交流测量信号。首先，所述N个光伏组件的交流测量信号分为M组，M大于等于2小于N的整数，每组包含Z个交流测量信号，Z为大于等于1的整数，每组中Z的个数可以不等；M组光伏组件的交流测量信号，在频率上，各组内与各组间的频率相同；幅值A在组内与组间可以不同，不同组中组内的各个交流测量信号的幅值A之和在组间相等，第一组中交流测量信号的幅值A之和等于第二组中交流测量信号的幅值A之和等于第M组中交流测量信号的幅值A之和；在相位上，各组内的初始相位相同，各组间任意相邻两组交流测量信号的相位依次相差360 0/M。可以理解的，将N个光伏功率变换设备分为M组，N个光伏组件的交流测量信号频率相同，由于不同组间的相位依次相差360 0/M，且组内各个交流测量信号振幅A相加在组间相等，在N个交流测量信号叠加中，振幅相互抵消，因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第一方面，在第五种可能的实施方式中，所述N个光伏组件的交流测量信号分为M组，同理将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组；主测量组首先启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到主测量组的变换电路中，进行光伏组件阻抗测量；主测量组在启动测量的同时，利用PLC通信等其他有线通信或wifi通 信等无线通信等其他通信手段，将测量启动信号主动发送至从测量组；从测量组接收到所述主测量组发送的测量启动信号，从测量组各自启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到各个从测量组到变换电路中，进行光伏组件的等效阻抗测量。
结合第一方面，在第六种可能的实施方式中，所述N个光伏组件的交流测量信号分为M组，同理将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组；主测量组首先启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到主测量组的变换电路中，进行光伏组件阻抗测量；从测量组主动检测到母线端口电压波动，并且母线端口电压波动的频率为所述主测量组的交流测量信号的设定频率；从测量组检测到母线端口电压波动后，确认光伏系统启动多机光伏等效阻抗测量，因此从测量组各自启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到各个从测量组的变换电路中，进行光伏组件的等效阻抗测量。
结合第一方面，在第七种可能的实施方式中，所述N个光伏组件的交流测量信号分为M组，同理将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组。主测量组首先启动光伏等效阻抗测量，从测量组在主测量组启动后各自分别启动光伏等效阻抗测量。从测量组根据从测量组与主测量组之间的启动时延，对从测量组生成的交流测量信号进行相位补偿，使得所述从测量组与主测量组对应的交流测量信号在同一个周期内的振幅叠加相互抵消。
结合第一方面，在第八种可能的实施方式中，对所述N个光伏组件进行等效阻抗测量，将所述N个光伏组件的交流测量信号加载到对应变换电路的时间有先后。首先，将所述N个变换电路的其中一个设置为主测量变换电路，其余的变换电路设置为从测量变换电路。所述主测量变换电路首先启动光伏组件等效阻抗测量，从测量变换电路在主测量变换电路启动后各自分别启动光伏组件等效阻抗测量。主从测量变换电路之间的信息同步的方式与所述第一方面的第六与第七种可能的实施方式中主从测量组的同步方式相同；主从测量变换电路之间由于存在启动时延，因此在从测量变换电路启动等效阻抗测量时，对从测量变换电路对应的交流测量信号进行相位补偿，使得所述从测量变换电路对应的交流测量信号与主测量变换电路对应的交流测量信号在同一个周期内的振幅叠加相互抵消。
结合第一方面，在第九种可能的实施方式中，所述变换电路为DC/DC变换电路，所述光伏系统还包括正负直流母线，N个所述DC/DC变换电路串联连接，N个所述DC/DC变换电路串联连接到所述正负直流母线之间。该DC/DC变换电路包括Boost电路，该Boost电路包括第一电感和第一开关管。Boost电路的正输入端通过第一电感和第一开关管连接Boost电路的负输出端。通过驱动信号控制Boost电路中第一开关管的导通与关断，从而实现对光伏组件的输出电压的控制。
结合第一方面，在第十种可能的实施方式中，所述变换电路分别为DC/AC逆变电路，所述光伏系统还包括正负交流母线，N个所述DC/AC逆变电路串联连接，N个所述DC/AC逆变电路串联连接到所述正负交流母线。该逆变电路包括第一相桥臂、第二相桥臂和第三相桥臂。第一相桥臂、第二相桥臂和第三相桥臂均并联至逆变电路的输入端，驱动信号包括第一驱动子信号、第二驱动子信号和第三驱动子信号。分别根据第一驱动子信号、第二驱动子信号和第三驱动子信号，控制第一相桥臂的开关管的导通与关断、第二相桥臂的开关管的导通与关断和第三相桥臂的开关管的导通与关断，从而实现对光伏组件的输出电压的控制。
结合第一方面，在第十一种可能的实施方式中，将N个光伏组件的交流测量信号加载到各自的变换电路中，首先根据每个交流测量信号及其各自对应的变换电路的参考电压和光伏组件的输出电压分别生成N个驱动信号，首先将每个变换电路的参考电压和所述对应交流测量信号叠加得到第二参考电压；利用所述第二参考电压和所述对应光伏组件的当前输出电压生成第一调制波，根据所述第一调制波生成所述驱动信号。或，将每个变换电路参考电压和所述对应光伏组件的当前输出电压生成第二调制波；将所述第二调制波和所述对应交流测量信号叠加得到第三调制波，根据所述第三调制波生成所述驱动信号。然后并根据这N个驱动信号分别控制对应N个光伏组件的输出电压，其中N，个参考电压为N个变换电路各自在向所述电网供电状态下的参考输入电压；分别获取在这N个驱动信号控制下N个光伏组件的输出电压和输出电流并基于N个交流测量信号各自对应频率对N个光伏组件的输出电压和输出电流进行频域滤波，得到N个光伏组件在所述N个交流测量信号各自对应频率的输出电压和输出电流；基于N个光伏组件在各自交流测量信号的对应频率下的输出电压和输出电流，分别确定N个光伏组件的等效阻抗。可以理解的，交流测量信号通过驱动电压的方式，直接加载到变换电路中，使光伏组件的输出电流与输出电压包含有交流测量信号的频率分量，最后获得对于频率分量下的等效阻抗，实现光伏组件等效阻抗的在线测量，不影响光伏系统的正常发电，适用性强。
结合第一方面，在第十二种可能的实施方式中，将N个光伏组件的交流测量信号加载到各自的变换电路中，首先根据每个交流测量信号及其各自对应的变换电路的参考电压和光伏组件的输出电压分别生成N个驱动信号，其中每个光伏组件的交流测量信号各自至少包含两个不同的频率，至少两个不同频率分别为第一频率和第二频率；分别获取在这N个驱动信号控制下N个光伏组件的输出电压和输出电流，进而分别基于对应所述交流测量信号第一频率与第二频率，对其进行频域滤波，获取在N个驱动信号控制下N个光伏组件在所述第一频率的输出电压和输出电流，以及所述N个光伏组件在所述第二频率的输出电压和输出电流；基于所述N个光伏组件在所述第一频率的输出电压和输出电流，以及所述N个光伏组件在所述第二频率的输出电压和输出电流，分别确定每个所述光伏组件的等效阻抗。可以理解的，每个光伏组件可通过一次集中注入至少两个不同频率的交流测量信号，进而根据每个光伏组件在至少两个不同频率中各频率的输出电压和输出电流，一次确定N个光伏组件在至少两个不同的频率下的等效阻抗，可有效减少工作量，提高工作效率，同时可有效提高光伏组件的等效阻抗的测量准确度，适用性强。
结合第一方面，在第十三种可能的实施方式中，每个所述交流测量信号的第一频率分量在同一个周期内振幅叠加相互抵消；每个所述交流测量信号的第二频率分量在同一个周期内振幅叠加相互抵消；或每个包含所述第一频率分量与第二频率分量的交流测量信号在同一个周期内上的振幅叠加相互抵消。可以理解的，可以通过一次等效阻抗测量同时获得至少两个不同频率下的等效阻抗，提高测量的效率与准确率，前提是保证不同频率所有测量信号的振幅叠加相互抵消，从而不会引起光伏系统的输出功率波动。
结合第一方面，在第十四种可能的实施方式中，确定所述每个变换电路的当前工作状态，并根据每个变换电路的当前工作状态分别确定各自的参考电压，该每个参考电压分别为对应变换电路处于限功率工作状态下的参考输入电压，或者每个对应变换电路处于非限功率工作状态下的参考输入电压。可以理解的，N个参考电压分别随着各自对应的变换电路的当前工作状态(即限功率工作状态或者非限功率工作状态)的变化而变化，因此可有效分别满足N个光伏功率变换设备处于不同工作状态下向电网供电的需求，灵活性高。
结合第一方面，在第十五种可能的实施方式中，所述N个光伏组件的交流测量信号在同一个周期内的振幅相互抵消，可以理解为，所述N个交流测量信号在相互叠加后的振幅为零或小于等于设置的阈值，所述设置的阈值，在同时对N个光伏组件进行等效阻抗测量时，N个交流测量信号所引起的波动不会超出光伏系统在工作状态下的正常的功率波动，因此可以保证在所述光伏系统正常工作的时候，同时得到N个光伏组件的等效阻抗。进一步的，只有一个交流测量信号对其对应的光伏组件进行等效阻抗测量时，所述一个交流测量信号的振幅小于等于设置的阈值，从而单个的交流测量信号也不会引起所述光伏系统的在正常工作状态的功率波动超出正常范围。可以理解的，所述N个交流测量信号的叠加信号不会超过设置的阈值，可以使所述N个交流测量信号的频率、振幅与相位的设置具有更高的灵活性。
第二方面，本申请提供了一种光伏系统，该光伏系统可以同时对系统内的N个光伏组串进行等效阻抗测量，且不会引起光伏系统输出功率的剧烈波动。所述光伏系统包括N个变换电路以及至少一个控制器，N为大于等于2的整数；所述每个变换电路的输入端连接对应的光伏组件，光伏组件与变换电路一一对应，所述每个变换电路的输出端串联，所述N个变换电路没有串联的第一端与第二端与电网连接，所述每个变换电路都与所述至少一个控制器连接；该光伏系统可以同时对N(N大于等于2)个光伏组件进行等效阻抗测量，该光伏系统中的至少一个控制器生成N个光伏组件的交流测量信号，N个光伏组件的交流测量信号的相位不同，N个光伏组件的交流测量信号在同一个周期内的振幅叠加相互抵消；所述至少一个控制器将N个光伏组件的交流测量信号分别加载到各自对应的变换电路中，从而使每个变换电路连接的光伏组件的输出电压与输出电流包含各自交流测量信号对应频率分量，根据各自交流测量信号对应频率分量分别确定N个光伏组件的等效阻抗。
结合第二方面，在第一种可能是实施方式中，光伏系统中的至少一个控制器分别生成N个光伏组件的交流测量信号，这N个光伏组件的交流测量信号的频率一致，为第一频率；同时这N个光伏组件的交流测量信号的相位不同，N个光伏组件的交流测量信号中任意相邻两个交流测量信号的相位依次相差360 0/N；可以理解的，光伏系统中的至少一个控制器分别生成N个频率相同、相位依次相差360 0/N的光伏组件的交流测量信号，这N个交流测量信号在同一个周期中振幅叠加相互抵消，因此不会引起光伏系统向电网传输电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第二方面，在第二种可能的实施方式中，光伏系统的至少一个控制器分别生成N个光伏组件的交流测量信号。首先，光伏系统将N个光伏组件的交流测量信号分为M组，M大于等于2小于N的整数；M组光伏组件的交流测量信号，在频率上，组内与组间的频率一致，为第一频率；在振幅上，组内与组间的振幅一致，为第一振幅；在相位上，组内的初始相位一致，组间的初始相位不同，在组间任意相邻两组交流测量信号的相位依次相差360 0/M。可以理解的，光伏系统将N个光伏组件的交流测量信号分为M组，M组光伏组件的交流测量信号频率相同、相位在组间依次相差360 0/M，在组与组之间的交流测量信号叠加中，振幅相互抵消，因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第二方面，在第三种可能的实施方式中，光伏系统的至少一个控制器分别生成N个光伏组件的交流测量信号。首先，光伏系统将N个光伏组件的交流测量信号分为M组，M大于等于2小于N的整数，每组包含Z个交流测量信号，Z为大于等于1的整数，每组中Z的个数可以不等；M组光伏组件的交流测量信号，在频率上，各组内的频率相同，各组 间的频率相同或不同；在相位上，各组内的初始相位不同，在组内任意相邻两个交流测量信号的相位依次相差360 0/Z。可以理解的，光伏系统将N个光伏功率变换设备组件的交流测量信号分为M组，在每个M组内，光伏组件的交流测量信号频率相同、相位依次相差360 0/Z。在组内的交流测量信号叠加中，振幅相互抵消，从而在M个组间的交流信号叠加中，振幅同样相互抵消。因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第二方面，在第四种可能的实施方式中，光伏系统的至少一个控制器分别生成N个光伏组件的交流测量信号。首先，光伏系统N个光伏组件的交流测量信号分为M组，M大于等于2，每组包含Z个交流测量信号，Z为大于等于1的整数，每组中Z的个数可以不等；M组光伏组件的交流测量信号，在频率上，各组内与各组间的频率相同；幅值A在组内与组间可以不同，不同组中组内的各个交流测量信号的幅值A之和在组间相等，即第一组中交流测量信号的幅值A之和等于第二组中交流测量信号的幅值A之和等于第M组中交流测量信号的幅值A之和；在相位上，各组内的初始相位相同，在组间任意相邻两组交流测量信号的相位依次相差360 0/M。可以理解的，光伏系统将N个光伏组件的交流测量信号分为M组，N个光伏组件的交流测量信号频率相同，由于不同组间的相位依次相差360 0/Z，且组内各个交流测量信号振幅A相加在组间相等。在N个交流测量信号叠加中，振幅相互抵消，因此不会引起光伏系统向电网传输的电能的功率波动，在同时测量N个光伏组件的同时保证光伏系统的正常运行。
结合第二方面，在第五种可能的实施方式中，光伏系统将N个光伏组件的交流测量信号分为M组，同理光伏系统也将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组；主测量组首先启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到主测量组的变换电路中，进行光伏组件阻抗测量；主测量组在启动测量的同时，利用PLC通信等有线通信或WiFi通信等无线通信或其他通信手段，将测量启动信号主动发送至从测量组；从测量组接收到所述主测量组发送的测量启动信号，从测量组各自启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到各个从测量组到光伏组件中，从测量组的光伏组件等效阻抗测量。
结合第二方面，在第六种可能的实施方式中，光伏系统将N个光伏组件的交流测量信号分为M组，同理光伏系统也将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组；主测量组首先启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到主测量组的变换电路中，进行光伏组件阻抗测量；从测量组主动检测到母线端口电压波动，并且母线端口电压波动的频率为主测量组的交流测量信号的设定频率；从测量组检测到母线端口电压波动后，确认光伏系统启动多机光伏等效阻抗测量，因此从测量组各自启动光伏等效阻抗测量，生成交流测量信号，将交流测量信号加载到各个从测量组到变换电路中，进行光伏组件阻抗测量。
结合第二方面，在第七种可能的实施方式中，所述光伏系统将N个光伏组件的交流测量信号分为M组，同理所述光伏系统也将所述N个变换电路也被分为M组，M组交流测量信号与M组变换电路一一对应，其中一组变换电路为主测量组，其余组变换电路为从测量组。主测量组首先启动光伏等效阻抗测量，从测量组在测量组启动后各自分别启动光伏等效阻抗测量。光伏系统中的从测量组根据从测量组与主测量组之间的启动时延，所述至少一个 控制器对从测量组生成的交流测量信号进行相位补偿，使得所述从测量组与主测量组对应的交流测量信号在同一个周期内的振幅叠加相互抵消。
结合第二方面，在第八种可能的实施方式中，光伏系统对所述N个光伏组件进行等效阻抗测量，光伏系统对不同的光伏组件进行等效阻抗测量启动顺序在实际应用用存在差异。首先，光伏系统将所述N个变换电路的其中一个设置为主测量变换电路，其余的变换电路设置为从测量变换电路。所述主测量变换电路首先启动光伏组件等效阻抗测量，从测量变换电路在主测量变换电路启动后各自分别启动光伏组件等效阻抗测量。所述光伏系统中主从测量变换电路之间的信息同步的方式与所述第一方面的第六与第七种可能的实施方式中主从测量组的同步方式相同；所述光伏系统中的主从测量变换电路之间由于存在启动时延，因此在从测量变换电路启动等效阻抗测量时，所述伏系统对从测量变换电路对应的交流测量信号进行相位补偿，使得所述从测量变换电路对应的交流测量信号与主测量变换电路对应的交流测量信号在同一个周期内的振幅叠加相互抵消。
结合第二方面，在第九种可能的实施方式中，光伏系统中的所述变换电路为DC/DC变换电路，所述光伏系统还包括正负直流母线，N个所述DC/DC变换电路串联连接，N个所述DC/DC变换电路串联连接到所述正负直流母线之间，该DC/DC变换电路包括Boost电路，该Boost电路包括第一电感和第一开关管。Boost电路的正输入端通过第一电感和第一开关管连接Boost电路的负输出端。所述光伏系统根据驱动信号控制第一开关管的导通与关断，从而实现对光伏组件的输出电压的控制。
结合第二方面，在第十种可能的实施方式中，光伏系统中的所述变换电路分别为DC/AC逆变电路，所述光伏系统还包括正负交流母线，N个所述DC/AC逆变电路串联连接，N个所述DC/AC逆变电路串联连接到所述正负交流母线之间。该逆变电路包括第一相桥臂、第二相桥臂和第三相桥臂。第一相桥臂、第二相桥臂和第三相桥臂均并联至逆变电路的输入端，驱动信号包括第一驱动子信号、第二驱动子信号和第三驱动子信号。光伏功率变换设备分别根据第一驱动子信号、第二驱动子信号和第三驱动子信号，控制第一相桥臂的开关管的导通时长、第二相桥臂的开关管的导通时长和第三相桥臂的开关管的导通时长，从而实现对光伏组件的输出电压的控制。
结合第二方面，在第十一种可能的实施方式中，光伏系统将N个光伏组件的交流测量信号加载到各自的变换电路中，首先至少一个控制器根据每个交流测量信号及其各自对应的变换电路的参考电压和光伏组件的输出电压分别生成N个驱动信号，首先光伏系统将每个变换电路的参考电压和所述对应交流测量信号叠加得到第二参考电压；然后光伏系统利用所述第二参考电压和所述对应光伏组件的当前输出电压生成第一调制波，最终光伏系统根据所述第一调制波生成所述驱动信号。或，所述光伏系统将每个变换电路参考电压和所述对应光伏组件的当前输出电压生成第二调制波；然后所述光伏系统将所述第二调制波和所述对应交流测量信号叠加得到第三调制波，最终光伏系统根据所述第三调制波生成所述驱动信号。所述N个驱动信号用于控制光伏系统中的N个光伏组件的输出电压，其中N个参考电压为所述光伏系统中的N个变换电路各自在向所述电网供电状态下的参考输入电压；所述至少一个控制器分别获取在这N个驱动信号控制下N个光伏组件的输出电压和输出电流，并基于N个交流测量信号各自对应频率对N个光伏组件的输出电压和输出电流进行频域滤波，得到N个光伏组件在所述N个交流测量信号各自对应频率的输出电压和输出电流；所述至少一个控制器基于N个光伏组件在各自交流测量信号的对应频率下的输出电压和输出电流，分别确定 N个光伏组件的等效阻抗。可以理解的，交流测量信号通过驱动电压的方式，直接加载到变换电路中，使光伏组件的输出电流与输出电压包含有交流测量信号的频率分量，最后获得对于频率分量下的等效阻抗，实现光伏组件等效阻抗的在线测量，不影响光伏系统的正常发电，适用性强。
结合第二方面，在第十二种可能的实施方式中，光伏系统将N个光伏组件的交流测量信号加载到各自的变换电路中，首先至少一个控制器根据每个交流测量信号及其各自对应的变换电路的参考电压和光伏组件的输出电压分别生成N个驱动信号，其中每个光伏组件的交流测量信号各自至少包含两个不同的频率，至少两个不同频率分别为第一频率和第二频率；所述至少一个控制器分别获取在这N个驱动信号控制下N个光伏组件的输出电压和输出电流，进而分别基于对应所述交流测量信号第一频率与第二频率，对其进行频域滤波，获取在N个驱动信号控制下N个光伏组件在所述第一频率下的输出电压和输出电流，以及所述N个光伏组件在所述第二频率下的输出电压和输出电流；基于所述N个光伏组件在所述第一频率下的输出电压和输出电流，以及所述N个光伏组件在所述第二频率下的输出电压和输出电流，确定所述光伏组件的等效阻抗。可以理解的，光伏系统可通过一次集中注入至少两个不同频率的交流测量信号到变换电路中，所述至少一个控制器进而一次性获得每个光伏组件在至少两个不同频率中各频率的输出电压和输出电流，因此一次确定N个光伏组件在至少两个不同的频率下的等效阻抗，可有效减少工作量，提高工作效率，同时可有效提高光伏组件的等效阻抗的测量准确度，适用性强。
结合第二方面，在第十三种可能的实施方式中，在光伏系统中，每个所述交流测量信号的第一频率分量在同一个周期内振幅叠加相互抵消；每个所述交流测量信号的第二频率分量在同一个周期内振幅叠加相互抵消；或每个包含所述第一频率分量与第二频率分量的交流测量信号在同一个周期内上的振幅叠加相互抵消。可以理解的，所述光伏系统可以通过一次等效阻抗测量同时获得至少两个不同频率下的等效阻抗，提高测量的效率与准确率，前提是保证不同频率所有测量信号的振幅叠加相互抵消，从而不会引起光伏系统的输出功率波动。
结合第二方面，在第十四种可能的实施方式中，光伏系统确定每个所述变换电路的当前工作状态，并根据每个变换电路的当前工作状态分别确定各自的参考电压，每个所述参考电压分别为对应变换电路处于限功率工作状态下的参考输入电压，或者每个光伏功率变换设备处于非限功率工作状态下的参考输入电压。可以理解的，所述光伏系统的N个参考电压分别随着各自对应的变换电路的当前工作状态(即限功率工作状态或者非限功率工作状态)的变化而变化，因此可有效分别满足N个光伏功率变换设备处于不同工作状态下向电网供电的需求，灵活性高。
结合第二方面，在第十五种可能的实施方式中，光伏系统中的控制器可以如上述实施方式中所述的，每一个变换电路对应一个控制器，所述控制器与所述变换电路一一对应，这样每个控制器单独控制一个变换电路，灵活性高，控制方式多种多样。在一些可行的实施例中，可以采用集中控制的方式，即一个控制器集中控制每个变换电路，所述每一个变换电路采用集中的控制，光伏系统中的控制器可以根据全局的信息做出最优的控制，从整体上提升系统的性能，效率更高。
结合第二方面，在第十六种可能的实施方式中，所述光伏系统中的所述N个光伏组件的交流测量信号在同一个周期内的振幅相互抵消，一般的，所述N个交流测量信号在相互叠加后形成的叠加信号的振幅为零或小于等于设置的阈值，上述第二方面的均基于所述叠加信号为零来设置所述N个交流测量信号的频率、振幅与相位。所述光伏系统还 可以根据所述叠加信号的振幅小于或等于设置的阈值来设置N个交流测量测量信号的频率、振幅与相位。可以理解的，通过目标函数设置的更加松弛，可以进一步的扩大可行解的范围，因此所述光伏系统在设置N个交流测量信号时具有更加灵活，也更加多样。一般的，所述光伏系统设置的阈值，在同时对N个光伏组件进行等效阻抗测量时，N个交流测量信号所引起的波动不会超出光伏系统在工作状态下的正常的功率波动，因此可以保证在所述光伏系统正常工作的时候，同时得到N个光伏组件的等效阻抗。同理的，光伏系统中只有一个交流测量信号对其对应的光伏组件进行等效阻抗测量时，所述一个交流测量信号的振幅小于等于设置的阈值，从而单个的交流测量信号也不会引起所述光伏系统的在正常工作状态的功率波动超出正常范围。
第三方面，本申请提供了一种光伏功率变换设备，所述光伏功率变换设备包括变换电路、控制器、输入端与输出端，所述输入端与对应光伏组件的输出端连接，所述输出端与电压母线连接或其他光伏功率变换设备连接，所述变换电路为DC/DC变换电路或DC/AC逆变电路；所述控制器采用了第一方面任一种可能的实施方式所提供的多机光伏组件的等效阻抗测量方法，所述控制器包括：
所述控制器用于在光伏组件平均输出电压保持在一定范围内时，生成至少一个交流测量信号，同时可以设置所述交流测量信号的频率、振幅与相位，所述至少一个交流测量信号相位不同，所述至少一个交流测量信号用于在同一个周期内的振幅相互或者与其它交流测量信号叠加抵消；同时所述控制器还根据参考电压、光伏组件的输出电压和交流测量信号生成至少一个驱动信号，并根据所述至少一个驱动信号控制变换电路对应连接的所述光伏组件分别输出包含交流测量信号频率的电压与电流，所述参考电压为所述光伏功率变换设备在向所述电网供电状态下的参考输入电压；
所述控制器，还用于同步N个光伏组件的等效阻抗测量，使所述光伏组件中同时进行等效阻抗测量。
所述控制器，还用于获取在所述至少一个驱动信号控制下的所述光伏组件在所述交流测量信号的频率下对应的输出电压和输出电流；同时用于根据至少一个光伏组件在所述交流测量信号的频率下对应的电压分量和电流分量，获得所述光伏组件的等效阻抗。
结合第三方面，在第一种可能的实施方式中，所述控制器生成交流测量信号包括：
所述控制器，用于生成指定频率、指定振幅、指定相位的交流测量信号，所述交流测量信号具有如所述第一方面与第二方面所述特征，使得所述生成的交流测量信号在同一个周期内相互振幅相互抵消；
结合第三方面，在第二种可能的实施方式中，所述控制器还根据参考电压、光伏组件的输出电压和交流测量信号生成驱动信号，包括:
所述控制器根据对应变换电路的参考电压和所述对应交流测量信号叠加得到第二参考电压；然后所述控制器将所述第二参考电压和所述对应光伏组件的当前输出电压生成第一调制波，并根据所述第一调制波生成所述驱动信号。
或，所述控制器根据对应变换电路参考电压和所述对应光伏组件的当前输出电压生成第二调制波；然后所述控制器将所述第二调制波和所述对应交流测量信号叠加得到第三调制波，并根据所述第三调制波生成所述驱动信号。
结合第三方面，在第三种可能的实施方式中，所述控制器还包括使所述的光伏组件同时进行等效阻抗测量，所述控制器具有通信功能，对于所述光伏系统中主测量组或主测量变 换电路，所述控制器用于将主测量组或主测量变换电路的测量启动信号发送到同一光伏系统的从测量组或从测量变换电路；对于光伏系统的从测量组或从测量变换电路，所述控制器用于获取同一光伏系统中主测量组或主测量变换电路中发出的启动测量信号，所述启动信号的传输协议可以利用PLC通信等有线通信或者wifi通信等无线通信等其他通信方式。
结合第三方面，在第四种可能的实施方式中，所述控制器还包括使所述的光伏组件同时进行等效阻抗测量，所述控制器可以不采用通信的方式，而是采用主动检测的方式进行不同光伏功率变换设备之间的同步。所述控制器获取所述光伏系统中的从测量组或从测量变换电路检测光伏功率变换设备电网侧的电压波动信号；然后所述控制器确认电压波动信号是否包含主测量组或主测量变换电路的等效阻抗测量信号对应频率的波动信号，最后所述控制器控制所述从测量组或从测量变换电路进行等效阻抗测量。
结合第三方面，在第五种可能的实施方式中，所述控制器用于获得所述光伏组件的等效阻抗，包括，所述控制器首先采集在驱动信号控制下的光伏组件的输出电压和输出电流；然后所述控制器根据交流测量信号的频率对光伏组件的采样输出电流和输出电压进行频域滤波，得到光伏组件的对应交流测量信号频率的输出电压和输出电流；最后所述控制器根据光伏组件的对应交流测量信号频率的输出电压和输出电流，计算光伏组件的等效阻抗。
应理解的是，本申请上述多个方面的实现和有益效果可互相参考。
附图说明
图1是现有技术提供的典型光伏组件阻抗测量系统的结构示意图；
图2是本申请提供的光伏系统的应用场景示意图；
图3是本申请提供的光伏系统的结构示意图；
图3-1、3-2、3-3是本申请提供的光伏系统的结构实例示意图；
图4是本申请提供的光伏组件的控制器的结构示意图；
图5是本申请提供的光伏系统的另一结构示意图；
图6是本申请提供的光伏系统的另一结构示意图；
图7是本申请提供的光伏系统的另一结构示意图；
图8是本申请提供的光伏系统的另一结构示意图；
图9是本申请提供的光伏系统的另一结构示意图；
图10是本申请提供的光伏系统的另一结构示意图；
图11是本申请提供的光伏组件的等效阻抗测量方法的流程示意图。
具体实施方式
本申请提供的光伏系统可适用于不同的应用场景，比如，光伏供电场景、光储混合供电场景等。其中，光伏供电场景中，供电电源为光伏组件；光储混合供电场景中，供电电源包括光伏组件和储能电池组串。下面以光伏供电场景为例进行说明。
参见图2，图2是本申请提供的光伏系统的应用场景示意图。本申请提供的光伏系统包括N个变换电路与至少一个控制器，N个光伏组件分别连接各自变换电路的输入端，光伏组件与变换电路一一对应，N个变换电路的输出端依次串联连接，N个变换电路没有串联的第一端与第二端与母线连接。在光伏供电场景下，变换电路可以为图1所示的DC/DC变换电路，电网可以为图1所示的交流电网。电网为交流电网时，所述光伏系统还包括逆变器，N个光伏功率变换设备各自串联后，位于首尾的光伏功率变换设备连接到逆变器，逆变器的输出端连接到交流 电网或家用交流用电设备。可选的电网也可以为直流电网，为直流设备使用。可选的图1中的变换电路也可以是DC/AC逆变电路，N个逆变电路输出端之间串联，N个逆变电路输出端没有串联的第一端与第二端与交流母线连接，交流母线直接与电网连接或家用交流用电设备。在光伏系统开始运行后，N个DC/DC变换电路可将与其输入端相连的光伏组件产生的直流电经过直流变换成电压为预设值的直流电，N个DC/DC变换电路串联后，将串联后直流电输出至逆变电路，逆变电路将N个DC/DC转换电路输出的直流电逆变为交流电，进而实现对交流电网或者交流负载(如家用设备)等多种类型的用电设备进行供电。由于光伏系统中的DC/DC变换电路可在向交流电网或者交流负载正常供电的基础上，实现同时对N个光伏组件的等效阻抗的测量，因此在光伏组件等效阻抗测量时并不会影响光伏系统的发电量，适用性强，效率高。
上述只是对本申请提供的光伏系统的应用场景进行示例，而非穷举，本申请不对应用场景进行限制。
下面结合图3至图10对本申请提供的光伏系统、多机等效阻抗测量方法以及光伏功率变换设备的工作原理进行示例说明。
参见图3，图3是本申请提供的光伏系统的一结构示意图。如图3所示，光伏系统包括4个光伏组件10和4个光伏功率变换设备11，4个光伏组件10分别连接各自光伏功率变换设备11的输入端，4个光伏功率变换设备11依次串联连接，4个光伏功率变换设备11没有串联的第一端与第二端与母线连接。其中，如图4所示，光伏功率变换设备111分别包括变换电路1111和控制器1112，变换电路1111的输入端连接光伏功率变换设备111的输入端，变换电路1111的输出端连接光伏功率变换设备111的输出端，变换电路1111用于将光伏组件101的输出电压变换为光伏功率变换设备111在向电网供电状态下的输出电压。控制器1112输出驱动电压到变换电路1111，该驱动电压电压中包含等效组抗测量信号，然后采集光伏组件的电压与电路，根据光伏组件的电压与电路输出该光伏组件的等效阻抗。
在一可选实施方式中，光伏系统同时对4个光伏组件10进行等效阻抗测量，4个光伏功率变换设备11各自的控制器分别产生4个交流测量信号，4个交流测量信号的频率相同，初始相位依次相差360 0/4，分别为：光伏功率变换设备111中控制器产生的交流测量信号的相位为0 0，光伏功率变换设备112中控制器产生的交流测量信号的相位为90 0，光伏功率变换设备113中控制器产生的交流测量信号的相位为180 0，光伏功率变换设备114中控制器产生的交流测量信号的相位为270 0。4个光伏组件10的交流测量信号在同一个周期内的振幅叠加相互抵消，然后4个光伏功率变换设备11中的控制器分别根据各自参考电压和交流测量信号生成4个驱动信号，并根据驱动信号分别控制4个光伏组件10的输出电压，其中，参考电压为4个光伏功率变换设备11分别在向电网供电状态下的参考输入电压。之后，4个光伏功率变换设备11中的控制器分别获取4个光伏组件10在驱动信号控制下各自交流测量信号对应频率的输出电压和输出电流，进而基于4个光伏组件10在各自交流测量信号对应频率下的输出电压和输出电流，同时确定4个光伏组件10的等效阻抗。
上述控制器具体结构如图5所示，图5是本申请提供的光伏功率变换设备的控制器的结构示意图。如图5所示，该控制器包括控制模块11121、同步模块11122和获取模块11123。
上述控制模块11121根据参考电压V ref1和频率为ω、相位为φ的交流测量信号V ref2生成驱动信号。控制模块生成驱动信号的同时，同步模块11122会将启动信号通知到光伏系统中的其他光伏功率变换设备，光伏系统中的其他光伏功率变换设备接收到启动信号后，同时开始进行等效阻抗测量。控制模块生成驱动信号后，将驱动信号输出至变换电路1111，以使驱动信号通过控制变换电路1111控制光伏组件101的输出电压v与输出电流i(即光伏功率变换设备111 的输入端电压与输入端电流)。之后，获取模块11123采集在驱动信号控制下时间间隔Δt内光伏组件101的输出电压和输出电流，并根据控制模块11121发送的频率ω，对时间间隔Δt内光伏组件101的输出电压和输出电流进行频域滤波，得到光伏组件101在频率ω的输出电压v(ω)和输出电流i(ω)，并根据光伏组件101在频率ω的输出电压v(ω)和输出电流i(ω)输，确定光伏组件101的等效阻抗Z(ω)。
进一步地，请参见图6，图6是本申请提供的光伏功率变换设备的控制器的另一结构示意图。如图6所示，控制模块11121包括控制单元111211和测量信号生成单元111212，获取模块11123包括采样单元111231和滤波单元111232，控制器还包括确定单元111233，同步模块11122用于各个光伏功率变换设备之间的同步。
光伏系统工作时，光伏系统中的4个光伏功率变换设备11处于运行状态，各个光伏功率变换设备分别根据自身以及与其连接的光伏组件的当前的工作状态确定参考电压V ref1，并将参考信号V ref1发送到光伏功率变换设备各自的控制单元中。其中，光伏系统中4个光伏功率变换设备11处于非限功率工作状态下时，各个光伏功率变换设备执行最大功率点跟踪(Maximum Power Point Tracking，MPPT)来最大化输出功率；光伏系统中4个光伏功率变换设备处于限功率工作状态下时，各个光伏功率变换设备主动限制输出功率。参考电压V ref1为各个光伏功率变换设备在向电网供电状态下的参考输入电压，换句话说，在各个光伏组件的等效阻抗的整个测量期间，可通过使各个光伏组件的输出电压平均值维持等于V ref1的方式，维持光伏系统的正常发电运行。
光伏系统启动对系统内的所有光伏组件同时进行等效阻抗测量时，光伏功率变换设备111中的测量信号生成单元111212根据设定的频率ω、相位φ和幅值A生成交流测量信号V ref2。与此同时，同步模块11122将光伏功率变换设备111启动测量等效阻抗的信号传递给该光伏系统中的光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114，光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自的同步模块检测到光伏功率变换设备111发出的启动信号后，同时启动测量各自连接的光伏组件的等效阻抗。具体的，光伏功率变换设备112对光伏组件102进行等效阻抗测量、光伏功率变换设备113对光伏组件103进行等效阻抗测量、光伏功率变换设备114对光伏组件104进行等效阻抗测量。光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自的测量信号生成单元根据设定的频率ω、相位φ和幅值A生成各自的交流测量信号。4个测量信号生成单元各自生成的交流测量信号频率ω相同、幅值A相同，相位φ不同，相位依次相差360 0/4。以测量信号生成单元111212生成的交流测量信号的相位为基准，即测量信号生成单元111212生成的交流测量信号的相位为基准为0 0，则光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自生成的交流测量信号的相位分别为、90 0、180 0、270 0。4个测量信号生成单元各自生成的交流测量信号在同一个周期内相互叠加抵消，即可以测量各自的光伏组件的等效阻抗，也不会引起光伏系统的功率波动。
4个光伏功率变换设备中各自的测量信号生成单元生成交流测量信号后，将各自的交流测量信号输入到控制单元。具体的，对于光伏功率变换设备111，将交流测量信号V ref2发送到控制单元111211中，控制单元根据参考信号V ref1、交流测量信号V ref2以及光伏组件101当时的输出电压V pv生成驱动信号。其中光伏组件输出电压V pv由光伏功率变换设备111的采样单元111231采集光伏组件101在时间间隔Δt内的输出电压，并将采集到输出电压V pv输出到控制单元111211。控制单元111211生成驱动信号后，控制单元111211将驱动信号输出至光伏功率变换设备111的变换电路1111中，光伏系统中其他控制单元同样将各自的驱动信号输出 到各自对应的变换电路中。该驱动信号用于控制变换电路1111中半导体开关器件的开关状态，从而在光伏组件101端口产生电压和电流包含对应的交流信号，同时维持光伏组件101的输出电压平均值等于参考电压V ref1。
特殊的，4个光伏功率变换设备中各自的交流测量信号后是由一个控制器中的信号生成单元产生，如控制器1112中信号生成单元111212同时生成四个不同的交流测量信号，然后分别将四个不同的交流测量信号输入到控制单元中，最终生成控制4个光伏功率变换设备的4个驱动信号，该种方式控制更加集中，不需要额外的同步设备，有利于系统的简化。
对于光伏功率变换设备111包含变换电路1111与光伏阻抗检测单元1112，其中变换电路1111为DC/DC变换电路，该DC/DC变换电路包括Boost电路，该Boost电路包括第一电感和第一开关管。Boost电路的正输入端通过第一电感和第一开关管连接Boost电路的负输出端。光伏功率变换设备根据驱动信号控制第一开关管的导通时长，从而实现对光伏组件的输出电压的控制。如图7，可选的，变换电路1111也可以为逆变器，该逆变器包括逆变电路，该逆变电路包括第一相桥臂、第二相桥臂和第三相桥臂。第一相桥臂、第二相桥臂和第三相桥臂均并联至逆变电路的输入端，驱动信号包括第一驱动子信号、第二驱动子信号和第三驱动子信号。光伏功率变换设备分别根据第一驱动子信号、第二驱动子信号和第三驱动子信号，控制第一相桥臂的开关管的导通时长、第二相桥臂的开关管的导通时长和第三相桥臂的开关管的导通时长，从而实现对光伏组件的输出电压的控制。
4个驱动信号输出到变换电路后，4个光伏组件的输出电压与输出电流中就包含有交流测量信号的信息。光伏发电系统中的4个光伏功率变换设备各自的采用单元采集各自对应光伏组件时间间隔Δt内的电压与电流。具体的，对于光伏功率变换设备111，利用其采用单元111231采集光伏组件101在时间间隔Δt内的的电压V pv与电流I pv。然后采集单元111231将采集光伏组件101的电压与电流输出到滤波单元111232中，滤波单元111232根据交流测量信号的频率ω对电压V pv与电流I pv进行滤波，得到在频率ω下的输出电压V pv(ω)与输出电流I pv(ω)。最后，确定单元111233根据光伏组件101在频率ω下的输出电压V pv(ω)与输出电流I pv(ω)，确定光伏组件101的等效阻抗Z(ω)＝V pv(ω)/I pv(ω)。光伏系统中其他的光伏功率变换设备，光伏功率变换设备102、光伏功率变换设备103与光伏功率变换设备104各自的滤波单元同样对各自的光伏组件的输出电压与输出电流进行滤波，然后各自得到在频率ω下对于的输出电压与输出电流，最后，根据滤波后的输出电压与输出电压获得各自光伏组件的等效阻抗。
光伏功率变换设备中的同步模块，用于同步光伏系统中的光伏功率变换设备，使光伏功率变换设备同时开始对各自连接的光伏组件进行等效阻抗测量。同步模块可以采用有线或无线的方式将信号发送到光伏系统中其他的光伏功率变换设备。采用有线通信方式时，可以采用PLC通信，PLC通信可以不用部署额外的物理通信线路，利用光伏功率变换设备之间连接的已有的电力线进行通信。同步模块将启动信号加载到光伏功率变换设备之间的电力线上，将启动信号发送到与其连接的其他光伏功率变换设备，其他光伏功率变换设备中的同步模块接收到启动信号后，各个光伏功率变换设备同时开始对与其连接的光伏组件进行等效阻抗测量。可选的，采用有线通信的方式也可以采用其他的技术，如以太等，在此不做限制。采用无线的通信方式时，可以避免物理通信线路的部署，降低光伏系统的维护成本。采用无线通信方式时，可以使用wifi、5G、蓝牙等多个通信方式，在此不做限制。
进一步的，光伏功率变换设备中的同步模块可以不采用通信模块，同步模块的作用是使光伏系统的中所有的光伏功率变换设备，同时对与其连接的光伏组件进行等效阻抗测量。如 图6中的光伏系统，光伏功率变换设备111开始对光伏组件101进行等效阻抗测量时，会在光伏功率变换设备111中加载包含交流测量信号的驱动信号，该交流测量信号会引起整个光伏系统轻微的抖动，该抖动包含了频率为ω的交流测量信号频率分量，因此，光伏系统中其他的光伏功率变换设备中的同步模块，通过检测该波动，检测到该波动中包含有频率为ω的信号分量，确认光伏功率变换设备111启动了光伏等效阻抗测量。然后光伏功率变换设备各自启动光伏等效阻抗测量。
由于所述光伏系统中的各个控制器启动测量光伏组件的等效阻抗的顺序有先后，而前述各个交流测量信号的相位设置的前提是所述光伏系统中的所有的控制器同时开始测量，因此在实际的测量过程中，如果还按照同时启动测量前提下设置的相位去设置实际中的交流测量信号相位，必然会出现光伏系统中所有的交流测量信号在同一个周期内振幅叠加不为零的状况。但是，由于存在同步模块，根据控制器所采用同步模块的类型，可以合理的得到各个光伏功率变换设备启动测量光伏组件等效阻抗的时延差，同时所述交流测量信号的频率已知，因此可以根据时延差与频率推到出实际交流测量信号与理论交流测量信号之间的相位差，对该相位进行补偿，将可以使得所述从测量组与主测量组对应的交流测量信号或第一个启动测量的光伏设备与其他光伏设备对应的交流测量信号在同一个周期内的振幅叠加相互抵消。
本实施例各个光伏功率变换设备中的测量信号生成单元产生的交流测量信号频率相同幅值相同，相位依次相差360 0/N，其中N为光伏系统中对光伏组件的数量，不同光伏组件间所承载的交流测量信号在同一个周期内相互抵消。因此光伏系统在测量系统内多个光伏组件的等效阻抗时，不会引起光伏系统的功率波动，保证光伏系统持续稳定的工作。
在另一可选的实施方式中，光伏系统同时对4个光伏组件10进行等效阻抗测量。首先光伏系统将4个光伏组件分为两组。如图7所示，光伏组件101与光伏功率变换设备111、光伏组件102与光伏功率变换设备112为第一组，光伏组件103与光伏功率变换设备113、光伏组件104与光伏功率变换设备114为第二组。分组后，第一组与第二组的光伏功率变换设备中各自的测量信号生成单元分别根据设定的频率ω、相位φ和幅值A生成交流测量信号。具体的，第一组与第二组生成的交流测量信号频率ω与幅值A在组内与组间均相同，而相位φ在组内相同在组间不同，组间依次相差360 0/2，2为整个光伏系统对光伏组件所分的组数，以第一组中的所产生的交流测量信号的相位为基准，即第一组中，光伏功率变换设备111与光伏功率变换设备112中各自产生的交流测量信号的相位为0 0，则第二组中，光伏功率变换设备113与光伏功率变换设备114中各自产生的交流测量信号的相位为180 0。4个测量信号生成单元各自生成的交流测量信号在同一个周期内相互叠加抵消，既可以测量各自的光伏组件的等效阻抗，也不会引起光伏系统的功率波动。
与前述实施例相同，本实施例同样需要同步模块。本实施例中，其中一组为主测量组，其余为从测量组，具体的，第一组为主测量组，第二组为从测量组。主测量组首先启动对本组内光伏组件101与光伏组件102的等效阻抗测量，光伏功率变换设备111与光伏功率变换设备112中各自的测量信号生成单元分别生成交流测量信号后，光伏功率变换设备111与光伏功率变换设备112将第一组的启动等效阻抗测量信号发送到从测量组，即第二组，第二组接收到第一组的启动等效阻抗测量信号后，开始对第二组内的光伏组件103与光伏组件104进行等效阻抗测量。从测量组内的光伏功率变换设备113与光伏功率变换设备114中各自的测量信号生成单元分别生成交流测量信号。
第一组与第二组的4个光伏功率变换设备中各自的测量信号生成单元生成交流测量信号 后，将各自的交流测量信号输入到控制单元。具体的，对于第一组中的光伏功率变换设备111，将交流测量信号V ref2发送到控制单元111211中，控制单元根据参考信号V ref1、交流测量信号V ref2以及光伏组件101当时的输出电压V pv生成驱动信号。其中光伏组件输出电压V pv由光伏功率变换设备111的采样单元111231采集光伏组件101在时间间隔Δt内的输出电压，并将采集到输出电压V pv输出到控制单元111211。控制单元111211生成驱动信号后，控制单元111211将驱动信号输出至光伏功率变换设备111的变换电路1111中，光伏系统中其他控制单元同样将各自的驱动信号输出到各自对应的变换电路中。该驱动信号用于控制变换电路1111中半导体开关器件的开关状态，从而在光伏组件101端口产生电压和电流包含对应的交流信号，同时维持光伏组件101的输出电压平均值等于参考电压V ref1。
第一组与第二组的4个驱动信号输出到变换电路后，4个光伏组件的输出电压与输出电流中就包含有交流测量信号的信息。光伏发电系统中的4个光伏功率变换设备各自的采用单元采集各自对应光伏组件时间间隔Δt内的电压与电流。具体的，对于光伏功率变换设备111，利用其采用单元111231采集光伏组件101在时间间隔Δt内的的电压V pv与电流I pv。然后采集单元111231将采集光伏组件101的电压与电流输出到滤波单元111232中，滤波单元111232根据交流测量信号的频率ω对电压V pv与电流I pv进行滤波，得到在频率ω下的输出电压V pv(ω)与输出电流I pv(ω)。最后，确定单元111233根据光伏组件101在频率ω下的输出电压V pv(ω)与输出电流I pv(ω)，确定光伏组件101的等效阻抗Z(ω)＝V pv(ω)/I pv(ω)。光伏系统中其他的光伏功率变换设备，第一组的光伏功率变换设备102、第二组的光伏功率变换设备103与光伏功率变换设备104各自的滤波单元同样对各自的光伏组件的输出电压与输出电流进行滤波，然后各自得到在频率ω下对于的输出电压与输出电流，最后，根据滤波后的输出电压与输出电压获得各自光伏组件的等效阻抗。
本实施例光伏系统中各个光伏功率变换设备中测量信号生成单元产生的交流测量信号在组内与组间频率ω相同幅值ω相同，相位φ在组内相同，组间不同，组间相位依次相差360 0/M，其中M为光伏系统中对光伏组件分组的组数，不同组间的交流测量信号在同一个周期内相互抵消，不同组之间的M相同。
可以看出，不同组间的测量信号生成单元各自生成的交流测量信号在同一个周期内相互叠加抵消，因此光伏系统在测量系统内多个光伏组件的等效阻抗时，不会引起光伏系统的功率波动，保证光伏系统持续稳定的工作。
在另一可选的实施方式中，光伏系统同时对6个光伏组件10进行等效阻抗测量。首先光伏系统将6个光伏组件分为两组。如图8所示，光伏组件101与光伏功率变换设备111、光伏组件102与光伏功率变换设备112、光伏组件103与光伏功率变换设备113为第一组，光伏组件104与光伏功率变换设备114、光伏组件105与光伏功率变换设备115、光伏组件106与光伏功率变换设备116为第二组，即每组包含3个光伏组件。同样的，分组也可以不均分，如第一组包含两个光伏组件，即光伏组件101与光伏功率变换设备111、光伏组件102与光伏功率变换设备112为第一组；第二组包含四个光伏组件，即光伏组件103与光伏功率变换设备113、光伏组件104与光伏功率变换设备114、光伏组件105与光伏功率变换设备115、光伏组件106与光伏功率变换设备116为第二组。分组后，第一组与第二组的光伏功率变换设备中各自的测量信号生成单元分别根据设定的根据设定的频率ω、相位φ和幅值A生成交流测量信号。
具体的，第一组与第二组均分，每个组包含三个光伏组件时：第一组与第二组生成的交 流测量信号幅值A在组内相同，组间相同或不同，具体的，第一组的振幅为A 1，第二组的振幅为A 2；频率ω在组内相同，在组间不同或相同，具体的，第一组的频率为ω 1，第二组的频率为ω 2；而相位φ在组内不同，组内依次相差360 0/3，3为组内中光伏组件的个数，组间的相位相同或不同。第一组中，以第一组中光伏功率变换设备111所产生的交流测量信号的相位为基准，即第一组光伏功率变换设备111所产生的交流测量信号的相位为0 0，第一组中光伏功率变换设备112所产生的交流测量信号的相位为120 0，第一组中光伏功率变换设备113所产生的交流测量信号的相位为240 0；第二组中，以第二组中光伏功率变换设备114所产生的交流测量信号的相位为基准，即第二组光伏功率变换设备114所产生的交流测量信号的相位为0 0，第一组中光伏功率变换设备115所产生的交流测量信号的相位为120 0，第二组中光伏功率变换设备116所产生的交流测量信号的相位为240 0。
具体的，第一组与第二组不均分，第一组包含两个光伏组件，第二组包含四个光伏组件时：第一组与第二组生成的交流测量信号幅值A在组内相同，在组间不同或相同，具体的，第一组的振幅为A 1，第二组的振幅为A 2；频率ω在组内相同，在组间不同或相同，具体的，第一组的频率为ω 1，第二组的频率为ω 2；而相位φ在组内不同，第一组中组内交流测量信号依次相差360 0/2，第二组中组内交流测量信号依次相差360 0/4，除数2和4为组内中光伏组件的个数，组间的相位相同或不同。第一组中，以第一组中光伏功率变换设备111所产生的交流测量信号的相位为基准，即第一组光伏功率变换设备111所产生的交流测量信号的相位为0 0，第一组中光伏功率变换设备112所产生的交流测量信号的相位为180 0；第二组中，以第二组中光伏功率变换设备113所产生的交流测量信号的相位为基准，即第一组光伏功率变换设备113所产生的交流测量信号的相位为0 0，第二组中光伏功率变换设备114所产生的交流测量信号的相位为90 0；第二组中光伏功率变换设备115所产生的交流测量信号的相位为180 0，第二组中光伏功率变换设备116所产生的交流测量信号的相位为270 0。
光伏系统中各组光伏功率变换设备生成交流测量信号之后，对各自对应的光伏组件进行等效阻抗测量，之后的步骤与前述实施例一致，不在详细赘述。需要指出的是，在确定单元，各个光伏功率变换设备中的滤波单元对采集单元采集到的各自对应光伏组件的输出电压与输出电流滤波时，需要根据各自对应的交流测量信号的频率ω进行滤波。具体的对比本实施例中，光伏系统对光伏组件均分的场景，第一组中各个滤波单元对各自对应光伏组件的输出电压V pv与输出电流I pv进行滤波，得到在频率ω 1下的输出电压V pv(ω 1)与输出电流I pv(ω 1)；第二组中各个滤波单元对各自对应光伏组件的输出电压V pv与输出电流I pv进行滤波，得到在频率ω 2下的输出电压V pv(ω 2)与输出电流I pv(ω 2)。最后，第一组中的各个光伏功率变换设备的确定单元根据各自光伏组件在频率ω 1下的输出电压V pv(ω 1)与输出电流I pv(ω 1)，确定光伏组件101的等效阻抗Z(ω 1)＝V pv(ω 1)/I pv(ω 1)；第二组中的各个光伏功率变换设备的确定单元根据各自光伏组件在频率ω 2下的输出电压V pv(ω 2)与输出电流I pv(ω 2)，确定光伏组件101的等效阻抗Z(ω 2)＝V pv(ω 2)/I pv(ω 2)。
本实施例光伏系统中各个光伏功率变换设备中测量信号生成单元所产生的交流测量信号在组内频率相同幅值相同，相位上，组内的各个交流测量信号相位依次相差360 0/Z，其中Z为组内光伏组件的个数，因此组内的交流测量信号在同一个周期内相互抵消。不同组之间的Z可以不同，不同组之间的频率ω与振幅A可以相同也可以不同。
可以看出，无论光伏系统对光伏组件分组是均分还是不均分，每组内的测量信号生成单元各自生成的交流测量信号在同一个周期内相互叠加抵消，则不同组之间叠加时也不会产生波动，因此光伏系统在测量系统内多个光伏组件的等效阻抗时，也不会引起光伏系统的功率 波动，保证光伏系统持续稳定的工作。
在另一可选的实施方式中，光伏系统同时对4个光伏组件10进行等效阻抗测量。首先光伏系统将4个光伏组件分为两组。如图9所示，第一组包含一个光伏组件，第二组包含3个光伏组件。具体的，光伏组件101与光伏功率变换设备111为第一组；光伏组件102与光伏功率变换设备112、光伏组件103与光伏功率变换设备113、光伏组件104与光伏功率变换设备114为第二组，即每组包含3个光伏组件。分组后，第一组与第二组的光伏功率变换设备中各自的测量信号生成单元分别根据设定的根据设定的频率ω、相位φ和幅值A生成交流测量信号。
具体的第一组与第二组生成的交流测量信号频率ω在组内与组间均相同；幅值A在组内相同，在组间不同，具体的，第一组交流测量信号的幅值A为A 1，第二组交流测量信号的幅值A为A 2，其中A 1/A 2＝3,3为第一组与第二组组内包含的光伏组件的数量比值。更一般的，组内中不同的交流测量信号的幅值可以不同，具体的，第一组光伏功率变换设备111产生的交流测量信号的幅值A为A 1，第二组光伏功率变换设备112产生的交流测量信号的幅值A为A 2、光伏功率变换设备113产生的交流测量信号的幅值A为A 3、光伏功率变换设备114产生的交流测量信号的幅值A为A 4，其中A 1＝A 2+A 3+A 4，A 2、A 3、A 4的值可以不同。而相位φ在组内相同，组间依次相差360 0/2，2为光伏系统对系统内的光伏组件分组的组数。具体的，以第一组中的所产生的交流测量信号的相位为基准，即第一组中光伏功率变换设备111产生的交流测量信号的相位为0 0，则第二组中，光伏功率变换设备112、光伏功率变换设备113与光伏功率变换设备114中各自产生的交流测量信号的相位为180 0。
光伏系统中各组光伏功率变换设备生成交流测量信号之后，对各自对应的光伏组件进行等效阻抗测量，之后的步骤与前述实施例一致，不在详细赘述。
本实施例中光伏系统中各个光伏功率变换设备中测量信号发生单元所产生的交流测量信号的频率在组间与组内均相同；在振幅A上，组内的不同交流测量信号的幅值A可以不同，不同组中组内的各个交流测量信号的幅值A之和在组间相等；在相位φ上，不同组间的交流测量信号的相位依次相差360 0/M，其中M为光伏系统对系统内光伏组件分组的组数，保证不同组的交流测量信号在同一个周期内相互抵消。因此光伏系统在测量系统内多个光伏组件的等效阻抗时，也不会引起光伏系统的功率波动，保证光伏系统持续稳定的工作。
总结，光伏系统可以对系统内的光伏组件进行不同的分组，然后根据分组情况，在不同的交流测量信号在同一个周期内相互抵消的前提下，生成特定的交流测量信号，特定的光伏功率变换设备所产生的交流信号的幅值、相位、频率都可以不同。这样保证了交流测量信号不会引起光伏系统的输出功率出现抖动，保证光伏系统在对多个光伏组件进行阻抗测量的同时，不会引起其工作状态，保证其输出频率不出现较大波动，提高效率。
在另一可选的实施方式中，光伏系统中光伏功率变换设备中的测量信号生成单元，同时生成至少两个不同的频率的交流测量信号，可以同时获得至少两个不同频率下光伏组件的等效阻抗，提高效率。
光伏系统启动对系统内的所有光伏组件同时进行等效阻抗测量时，如图10所示,光伏功率变换设备111中的测量信号生成单元111212根据设定的频率ω(ω 1,ω 2)、相位φ和幅值A生成交流测量信号V ref2(ω 1,ω 2)，交流测量信号中包含了两个频率(ω 1,ω 2)。基于光伏系统中的同步模块，光伏系统中的其他光伏功率变换设备同时对各自连接的光伏组件进行等效阻 抗测量。具体的，光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自的测量信号生成单元根据设定的频率ω(ω 1,ω 2)、相位φ和幅值A生成各自的交流测量信号，每个交流测量信号都包含两个频率第一频率和第二频率(ω 1,ω 2)。
具体的，4个测量信号生成单元各自生成的交流测量信号均包含第一频率ω 1与第二频率ω 2，ω 1与ω 2不同。对于四个测量信号生成单元生成的第一频率ω 1分量的交流测量信号，各自的频率ω 1与幅值A相同，相位φ不同，相位依次相差360 0/4。以测量信号生成单元111212生成的第一频率ω 1分量的交流测量信号的相位为基准，即测量信号生成单元111212生成的第一频率ω 1分量的交流测量信号的相位为0 0，则光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自生成的第一频率ω 1分量的交流测量信号的相位分别为90 0、180 0、270 0。对于四个测量信号生成单元生成的第二频率ω 2分量的交流测量信号，各自的频率ω 2与幅值A相同，相位φ不同，相位依次相差360 0/4。以测量信号生成单元111212生成的第二频率ω 2分量的交流测量信号的相位为基准，即测量信号生成单元111212生成的第二频率ω 2分量的交流测量信号的相位为0 0，则光伏功率变换设备112、光伏功率变换设备113以及光伏功率变换设备114中各自生成的第二频率ω 2分量的交流测量信号的相位分别为90 0、180 0、270 0。第一频率分量ω 1的交流信号频率的相位与第二频率分量ω 2的交流信号频率的相位之间可以没有关系。这样，4个第一频率分量的交流测量信号在同一个周期内相互叠加抵消，4个第二频率分量的交流测量信号在同一个周期内相互也叠加抵消，则4个第一频率分量与4个第二频率分量在同一个周期内的信号仍然相互抵消，因此光伏系统即可以测量各自的光伏组件的等效阻抗，也不会引起光伏系统的功率波动，具有系统稳定性，同时可以获得光伏组件在多个不同频率下的等效阻抗，提高测量效率。
可选的，光伏功率变换设备111中的测量信号生成单元111212生成的交流测量信号至少包含两个不同频率还包括第三频率ω 3,…,第n频率ω n，其中，n为大于1的整数。对于光伏组件101，光伏功率变换设备111中的确定单元111233根据光伏组件101在第一频率ω 1的输出电压V pv(ω 1)和输出电流I pv(ω 1)，光伏组件101在第二频率ω 2的输出电压V pv(ω 2)和输出电流I pv(ω 2)，…，以及光伏组件101在第n频率ω n的输出电压V pv(ω n)和输出电流I pv(ω n)，得到光伏组件101的等效阻抗分量Z(ω 1)＝V pv(ω 1)/I pv(ω 1)，Z(ω 2)＝V pv(ω 2)/I pv(ω 2)，…，Z(ω n)＝V pv(ω n)/I pv(ω n)。之后，确定单元111233根据光伏组件101的等效阻抗分量Z(ω 1),Z(ω 2)，…，Z(ω n)，得到光伏组件101的等效阻抗Z(ω)＝{Z(ω 1),Z(ω 2),…,Z(ω n)}。同理，光伏组件102、光伏组件103与光伏组件104也可以同时获得在不同频率下的等效阻抗。
各个光伏功率变换设备中的控制单元根据各自的参考电压、交流测量信号以及当前对应光伏组件的电压生成驱动信号，其中光伏组件的交流测量信号各自至少包含两个不同的频率，至少两个不同频率包括第一频率和第二频率；各个光伏功率变换设备中的采集单元获取在对应驱动信号控制下所述的光伏组件的输出电压与输出电流，该光伏组件的输出电压与输出电流包含有第一频率分量与第二频率分量，然后各个滤波单元根据第一频率与第二频率，对光伏组件的输出电压与输出电流进行滤波，分别获得光伏组件在第一频率分析的输出电压和输出电流以及光伏组件在第二频率的输出电压和输出电流；光伏功率变换设备基于各个光伏组件在所述第一频率的输出电压和输出电流以及光伏组件在第二频率的输出电压和输出电流，确定所述光伏组件的等效阻抗。
进一步，本申请中的以上实施例均是以光伏系统中不同的交流测量信号在同一个周期内振幅相互叠加抵消为零的目标来设置各个交流测量信号的频率、相位、振幅。同样的，在一 些光伏系统对功率波动要求较低的场景，比如功率波动只要小于某个阈值即可以保证所述光伏系统的正常工作。因此，在上述光伏系统中进行光伏组件的等效阻抗测量时，可以按照所述不同的交流测量信号在同一个周期内振幅叠加小于设定阈值为目标来设置各个交流测量信号的频率、相位以及振幅。具体的，将设置的目标的范围扩大，可以更灵活的设置交流测量信号的频率、振幅与相位，使得所述光伏系统更灵活，适应性强。
一般的，该实施例也可以同前述的实施例结合，根据不同的分组，在保证光伏系统中的交流测量信号在同一个周期内相互抵消的前提下，通过设计频率、相位、幅值获得不同的交流测量信号组合。
参见图11，图11是本申请提供的多机光伏组件的等效阻抗测量方法的流程示意图。本申请实施例提供的多机光伏组件的等效阻抗测量方法适用于图5-图10所示的支持多机光伏组件等效阻抗测量的光伏系统。多机光伏组件的等效阻抗测量方法可包括步骤：
S1，生成N个振幅叠加相互抵消的交流测量信号。
首先生成N个交流测量信号，所述N个交流测量信号在同一个周期内的振幅叠加相互抵消。一般的，所述N个交流测量信号相互叠加得到叠加信号，所述叠加信号的振幅小于等于设定阈值，当所述叠加信号的振幅小于或等于设定阈值时，所述叠加信号的不会影响光伏系统的正常的工作，所述叠加信号对光伏系统的影响不会超过所述光伏系统的承受范围。
一般的，可以采用相移的方式生成N个交流测量信号，所述N个交流测量信号的相位不同，一种可行的实施方式为，所述N个交流测量信号的频率和振幅一致，所述N个交流测量信号的任意相邻两个交流测量信号的相位相差360 0/N。
S2，将N个交流测量信号加载到变换电路中。
首先根据每个变换电路的参考电压和所述对应交流测量信号叠加得到第二参考电压；然后再根据所述第二参考电压和所述对应光伏组件的当前输出电压生成第一调制波，并根据所述第一调制波生成所述驱动信号，利用所述控制信号控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流；
或，首先根据每个变换电路参考电压和所述对应光伏组件的当前输出电压生成第二调制波；然后再根据所述第二调制波和所述对应交流测量信号叠加得到第三调制波，并根据所述第三调制波生成所述驱动信号，利用所述控制信号控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流。
S3，获取N个驱动电压控制的光伏组件的输出电压与输出电流。
根据N个驱动电压控制所述变换电路，具体的，所述驱动电压可以通过控制所述变换电路的开关管的导通与关断。所述变换电路可以对光伏组件的输出电压进行转换，而所述光伏组件的输出功率是一定的，通过控制所述光伏组件的输出电压进而可以控制所述光伏组件的输出电流，由于驱动电压中包含了所述交流测量信号，因此光伏组件的输出电压和输出电流中也包含交流测量信号的频率分量。
S4，根据N个光伏组件的输出电压和输出电流，得到N个光伏组件的等效阻抗。
获得所述N个光伏组件的输出电压与输出电流，所述输出电压与输出电流中包含有所述交流测量信号的频率分量，根据所述交流测量信号的频率对所述N个光伏组件的输出电压与输出电流进行滤波，得到所述交流测量信号对应频率下的输出电压与输出电流，在根据所述所述交流测量信号对应频率下的输出电压与输出电流做比值，得到所述N个光伏组件的等效阻抗。
本实施例组内产生的交流测量信号各自至少包含两个不同频率ω(ω 1,ω 2)；不同的频率分量的交流测量信号的幅值A相同，相位φ依次相差360 0/N，其中N为该频率分量的交流测量信号的个数，因此不同频率分量的交流测量信号在同一个周期内信号叠加相互抵消，整个光伏系统中产生的不同频率分量的交流测量信号在同一个周期内同样叠加相互抵消。因此光伏系统在测量系统内多个光伏组件的等效阻抗时，也不会引起光伏系统的功率波动，保证光伏系统持续稳定的工作。同时可以一次性获得光伏组件在多个不同频率下的等效阻抗，提高测量效率。
以上，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (22)

  1. 一种光伏系统，包括N个变换电路以及至少一个控制器，所述N为大于等于2的整数；
    所述每个变换电路的输入端连接对应的光伏组件，所述每个变换电路的输出端串联，所述每个变换电路都连接到所述至少一个控制器的一个；
    所述至少一个控制器在光伏组件平均输出电压保持在一定范围内时，生成N个交流测量信号，所述N个交流测量信号相位不同，所述N个交流测量信号在同一个周期内的振幅叠加相互抵消；
    所述至少一个控制器用于控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流，其中所述电压和电流中具有交流测量信号频率的电压分量与电流分量用于测量对应光伏组件的等效阻抗。
  2. 根据权利要求1所述的光伏系统，其特征在于，所述N个交流测量信号在同一个周期内的振幅叠加相互抵消，包括：
    所述至少一个控制器生成的所述N个交流测量信号在同一个周期内相互叠加，形成叠加周期信号，所述叠加周期信号的振幅小于或等于预设阈值，所述光伏系统正常工作时，所述至少一个控制器的交流测量信号小于或等于所述预设阈值。
  3. 根据权利要求1-2任一所述的光伏系统，其特征在于，所述N个交流测量信号，包括：
    所述N个交流测量信号的频率一致；
    所述N个流测量信号中任意相邻两个交流测量信号的相位相差360°/N。
  4. 根据权利要求1-2任一所述的光伏系统，其特征在于，所述N个交流测量信号，包括：
    所述光伏系统将所述N个交流测量信号分为M组，M大于等于2小于N的整数，每组包含Z个交流测量信号，Z大于等于1的整数；
    所述M组交流测量信号的频率相同；
    所述M组中每一组内的交流测量信号的相位相同，所述M组交流测量信号中任意相邻两组交流测量信号的相位相差360°/M。
  5. 根据权利要求1-2任一所述的光伏系统，其特征在于，所述N个交流测量信号，包括：
    所述光伏系统将所述N个交流测量信号分为M组，M大于等于2小于N的整数，每组包含Z个交流测量信号，Z大于等于2的整数；
    所述M组交流测量信号的频率在组内相同；
    所述M组中每组内任意相邻的交流测量信号的相位相差360°/Z。
  6. 根据权利要求1所述的光伏系统，其特征在于，每个所述N个交流测量信号至少包含两个不同的频率；
    所述至少一个控制器，用于分别获取所述不同频率下的所述光伏组件的输出电压和输出电流，以获取每个所述光伏组件在不同频率下的等效阻抗。
  7. 根据权利要求6所述的光伏系统，其特征在于，所述至少两个不同频率为第一频率和第二频率，包括：
    每个所述交流测量信号的第一频率分量在同一个周期内振幅叠加相互抵消；每个所述交流测量信号的第二频率分量在同一个周期内振幅叠加相互抵消；或每个包含所述第一频率分量与第二频率分量的交流测量信号在同一个周期内上的振幅相互叠加后实现相互抵消。
  8. 根据权利要求1-5任一项所述的光伏系统，其特征在于，所述光伏系统将所述N个交流测量信号分为M组，包括：
    所述光伏系统将N个变换电路也分为M组，M组交流测量信号与M组变换电路一一对应，所述M组变换电路其中一组为主测量组，其余组为从测量组；
    或，所述至少一个控制器生成所述N个交流测量信号，所述光伏系统将所述N个交流测量信号的其中一个交流测量信号对应的变换电路设置为主测量变换电路，其余变换电路为从测量变换电路。
  9. 根据权利要求8所述的光伏系统，其特征在于，所述光伏系统用于：
    所述至少一个控制器首先启动测量所述主测量组或主测量变换电路对应连接的光伏组件的等效阻抗，并引起母线端口的电压波动；
    所述从测量组或从测量变换电路对应的控制器检测到母线端口的电压波动后，所述至少一个控制器启动测量所述从测量组或从测量变换电路对应连接的光伏组件的等效阻抗。
  10. 根据权利要求1-7任一项所述的光伏系统，其特征在于，所述至少一个控制器还包括同步模块，所述同步模块包括通信单元：
    所述通信单元为有线通信单元或无线通信单元，所述通信单元用于接收光伏系统的光伏组件等效阻抗测量启动信号后，所述至少一个控制器启动测量对应光伏组件的等效阻抗。
  11. 根据权利要求1所述的光伏系统，其特征在于，所述至少一个控制器用于控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流，包括：
    所述光伏系统中每个变换电路的参考电压和所述对应交流测量信号叠加得到第二参考电压；所述第二参考电压和所述对应光伏组件的当前输出电压生成第一调制波，并根据所述第一调制波生成所述驱动信号，以控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流；
    或，所述光伏系统中每个变换电路参考电压和所述对应光伏组件的当前输出电压生成第二调制波；将所述第二调制波和所述对应交流测量信号叠加得到第三调制波，并根据所述第三调制波生成所述驱动信号，以控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流。
  12. 根据权利要求1所述的光伏系统，其特征在于，所述包含交流测量信号频率的电压与电流用于测量对应光伏组件的等效阻抗，包括：
    所述至少一个控制器分别获取所述光伏组件的输出电压和输出电流，然后分别基于对应所述交流测量信号的频率，对每个所述光伏组件的输出电压和输出电流进行频域滤波，分别得到每个光伏组件在对应交流测量信号频率下的输出电压和输出电流，以基于每个所述光伏组件在对应交流测量信号对应频率下的输出电压和输出电流获取每个所述光伏组件的等效阻抗。
  13. 根据权利要求1或7所述的光伏系统，其特征在于，所述至少两个不同频率为第一频率和第二频率，包括：
    所述至少一个控制器，用于分别获取所述光伏组件的输出电压和输出电流，进而分别基于对应所述交流测量信号第一频率与第二频率，对每个所述光伏组件的输出电压和输出电流进行频域滤波，从而分别得到每个光伏组件在所述第一频率下的输出电压和输出电流和在所述第二频率下的输出电压和输出电流，以分别获得每个所述光伏组件对应所述第一频率和第二频率的等效阻抗。
  14. 根据权利要求1-13任一项所述的光伏系统，其特征在于，所述变换电路为DC/DC变换电路，所述光伏系统还包括正负直流母线，N个所述DC/DC变换电路串联连接在所述正负直流母线之间。
  15. 根据权利要求1-13任一项所述的光伏系统，其特征在于，所述变换电路为DC/AC逆变电路，所述光伏系统还包括正负交流母线，N个所述DC/AC逆变电路串联或并联连接连接到所述正负交流母线之间。
  16. 一种光伏组件的等效阻抗测量方法，用于光伏系统中N个光伏组件的阻抗测量，其特征在于，所述N个光伏组件的输出端分别用于连接对应变换电路输入端，N个所述变换电路的输出端串联，所述方法包括：
    当光伏组件平均输出电压保持在一定范围内时，生成N个交流测量信号，所述交流测量信号的相位不同，使得所述N个交流测量信号在同一个周期内的振幅叠加相互抵消；
    控制N个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流，其中所述电压和电流包含的交流测量信号的频率分量用于测量对应光伏组件的等效阻抗。
  17. 根据权利要求16所述的方法，其特征在于，其特征在于，使得所述N个交流测量信号在同一个周期内的振幅叠加相互抵消，包括：
    生成的所述N个交流测量信号在同一个周期内相互叠加，形成叠加周期信号，所述叠加周期信号的振幅小于光伏系统设置阈值，所述叠加周期信号的振幅小于光伏系统设置阈值时，所述光伏系统可以正常工作。
  18. 根据权利要求16-17任一项所述的方法，其特征在于，生成N个交流测量信号，包括：
    所述N个交流测量信号的频率一致；
    所述N个流测量信号中任意相邻两个交流测量信号的相位依次相差为360°/N。
  19. 根据权利要求16-17任一项所述的方法，其特征在于，生成N个交流测量信号，包括：
    将所述N个交流测量信号分为M组，M为大于等于2小于N的整数，每组包含Z个交流测量信号，Z大于等于1的整数；
    所述M组交流测量信号的频率一致；
    所述M组中每一组内的交流测量信号的相位相同，所述M组交流测量信号中任意相邻两组交流测量信号相位相差360°/M。
  20. 根据权利要求16-17任一项所述的方法，其特征在于，生成N个交流测量信号，包括：
    将所述N个交流测量信号分为M组，M为大于等于2小于N的整数，每组包含Z个交流测量信号，Z大于等于1的整数；
    所述M组交流测量信号的频率在组内相同；
    所述M组中每一组内任意相邻的交流测量信号的相位相差360°/Z。
  21. 一种光伏功率变换设备，所述光伏功率变换设备包括变换电路、控制器、输入端与输出端，所述输入端用于与光伏组件的输出端连接，所述输出端与电压母线连接或与其他光伏功率变换设备连接，等效阻抗测量所述控制器包括：
    所述控制器用于在光伏组件平均输出电压保持在一定范围内时，生成至少一个交流测量信号，所述至少一个交流测量信号相位不同，所述至少一个交流测量信号用于在同一个周期内的振幅相互或者与其它交流测量信号叠加抵消；
    所述控制器用于控制至少一个变换电路对应连接的光伏组件分别输出包含交流测量信号频率的电压与电流，其中所述电压和电流中具有交流测量信号频率的电压分量与电流分量用于测量对应光伏组件的等效阻抗。
  22. 根据权利要求21所述的光伏功率变换设备，其特征在于，所述控制器用于根据权利要求17-20中的任一项所述的光伏组件的等效阻抗测量方法生成交流测量信号。
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