WO2016000500A1 - 光伏逆变电路的控制方法及控制装置 - Google Patents

光伏逆变电路的控制方法及控制装置 Download PDF

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Publication number
WO2016000500A1
WO2016000500A1 PCT/CN2015/079884 CN2015079884W WO2016000500A1 WO 2016000500 A1 WO2016000500 A1 WO 2016000500A1 CN 2015079884 W CN2015079884 W CN 2015079884W WO 2016000500 A1 WO2016000500 A1 WO 2016000500A1
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Prior art keywords
boost converter
control
level
voltage
inverter
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PCT/CN2015/079884
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English (en)
French (fr)
Inventor
丁杰
陶磊
邹海晏
孙龙林
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the invention belongs to the technical field of photovoltaic power generation, and particularly relates to a control method and a control device for a photovoltaic inverter circuit.
  • Photovoltaic power generation technology has been widely used. Inverters are very important components in photovoltaic inverter circuits.
  • the current five-level inverters have lower grid-connected current ripple and lower switching losses, and have lower grid-connected current harmonic distortion than traditional two- or three-level inverters. And higher efficiency.
  • the solar cell array 100 is connected to the positive input bus and the negative input bus.
  • the voltage of the positive input bus relative to the midpoint is V1Pos, and the voltage of the midpoint relative to the negative input bus is V1Neg.
  • the positive input bus voltage is boosted by the first Boost converter 201 to obtain a positive total bus voltage
  • the negative input bus voltage is boosted by the second Boost converter 202 to obtain a negative total bus voltage
  • the voltage of the positive total bus relative to the midpoint is V2Pos.
  • the voltage at the midpoint relative to the negative total bus is V2Neg.
  • the five-level inverters 301, 302, and 303 are capable of outputting electrical signals having level values of V2Pos, V1Pos, 0, -V1Neg, and -V2Neg.
  • C1 is the positive input bus capacitance
  • C2 is the negative input bus capacitance
  • C3 is the positive total bus capacitance
  • C4 is the negative total bus capacitance.
  • the inverter group of the single-phase photovoltaic inverter circuit only includes A five-level inverter
  • the inverter group of the two-phase photovoltaic inverter circuit includes two five-level inverters. That is to say, the inverter group of the photovoltaic inverter circuit includes at least one five-level inverter.
  • the configuration of the five-level inverter is not limited to that shown in Fig. 1, and a five-level inverter of another configuration is also possible.
  • the five-level inverter is directly started in the five-level mode, which causes large fluctuations in the input voltage and input power of the solar cell array, and the startup process is not stable.
  • an object of embodiments of the present invention is to provide a control method and a control device for a photovoltaic inverter circuit to reduce fluctuations in input voltage and input power of a solar cell array during startup, so that the startup process is smoother.
  • the present invention provides the following technical solutions:
  • a method for controlling a photovoltaic inverter circuit comprising a first Boost boost converter, a second Boost converter, and an inverter group, the inverter group including at least one five-level inverter
  • the control method includes:
  • the charging operation is stopped, and the phase locked loop of the power grid is controlled to perform a phase locking operation;
  • the five-level inverter is activated in a three-level mode, so that the five-level inverter can output the power values of V2Pos, 0, and -V2Neg. Signaling, performing voltage loop control and current loop control on the five-level inverter;
  • the five-level inverter is controlled to operate in a five-level mode.
  • the first preset condition includes any one of the following: a total bus voltage reaches a first voltage threshold; or a time for charging the positive total bus capacitance and the negative total bus capacitance The first time threshold is reached.
  • the second preset condition includes any one of the following: the total bus voltage reaches a set value; or the five-level inverter runs in a three-level mode for a time Two time thresholds.
  • the method when the second preset condition is met, the method further includes: performing current loop control on the first Boost converter and the second Boost converter.
  • the method further includes: performing MPPT maximum power on the first Boost converter and the second Boost converter Point tracking control to cause the solar array to output maximum power.
  • the invention also discloses a control device for a photovoltaic inverter circuit, the photovoltaic inverter circuit comprising a first Boost boost converter, a second Boost converter and an inverter group, the inverter group comprising at least one five a level inverter, the control device comprising:
  • a first control unit configured to charge the positive total bus capacitor and the negative total bus capacitor after receiving the power-on command
  • a second control unit configured to stop the charging operation when the first preset condition is met, and control the phase locked loop of the power grid to perform a phase locking operation
  • a third control unit configured to activate the five-level inverter in a three-level mode after the phase-locked loop completes the phase-locking operation, so that the five-level inverter can output a level value of V2Pos , 0 and -V2Neg electrical signals, voltage loop control and current loop control of the five-level inverter;
  • a fourth control unit when the second preset condition is met, performing voltage ring control on the first Boost converter and the second Boost converter to control the first Boost converter and the second Boost
  • the converter is started at no load
  • a fifth control unit configured to control the five-level inverter to operate in a five-level mode after the input voltage and the input current of the first Boost converter and the second Boost converter are stabilized.
  • the second control unit includes a first determining module or a second determining module; the first determining module is configured to determine that the total bus voltage reaches a first voltage threshold a preset condition; the second determining module is configured to determine that the first preset condition is met when a time for charging the positive total bus capacitor and the negative total bus capacitor reaches a first time threshold.
  • the fourth control unit includes a third determining module or a fourth determining module; and the third determining module is configured to determine that the second preset is met when the total bus voltage reaches a set value The fourth determining module is configured to determine that the second preset condition is met when the time that the five-level inverter is operating in the three-level mode reaches the second time threshold.
  • the above control device further includes a sixth control unit; the sixth control unit satisfies the The current loop control is performed on the first Boost converter and the second Boost converter when two preset conditions are met.
  • control device further includes a seventh control unit, wherein the seventh control unit is configured to: after the fifth control unit controls the five-level inverter to operate in a five-level mode
  • the Boost converter and the second Boost converter perform MPPT maximum power point tracking control to cause the solar array to output maximum power.
  • the beneficial effects of the present invention are: the control method of the photovoltaic inverter circuit disclosed in the present invention, starting the five-level inverter in the inverter group in a three-level mode, so that the five-level inverter output
  • the power causes a disturbance; after that, controlling the first Boost converter and the second Boost converter to start with no load, the power disturbance caused by the solar array is minimized; when the five-level inverter is switched to the five-level mode Since the first Boost converter and the second Boost converter have started the voltage loop control, the disturbance to the input voltage of the solar cell array can be reduced, and the power disturbance to the solar cell array can be reduced accordingly.
  • the control method disclosed in the present invention can reduce the fluctuation of the input voltage and the input power of the solar cell array during the startup process of the photovoltaic inverter circuit, so that the startup process is smoother.
  • FIG. 1 is a schematic structural view of a conventional photovoltaic inverter circuit
  • FIG. 2 is a flow chart of a control method of a photovoltaic inverter circuit disclosed in the present invention
  • FIG. 3 is a schematic structural diagram of a five-level inverter topology
  • FIG. 4 is a schematic diagram of a specific application scenario of the photovoltaic inverter circuit shown in FIG. 1;
  • FIG. 6 is a waveform diagram obtained by simulating a process of starting a photovoltaic inverter circuit based on an existing method
  • FIG. 7 is a schematic structural view of a control device of a photovoltaic inverter circuit disclosed in the present invention.
  • FIG. 8 is a schematic structural diagram of another control device of the photovoltaic inverter circuit disclosed in the present invention.
  • the invention discloses a control method of a photovoltaic inverter circuit, so as to reduce the fluctuation of the input voltage and the input power of the solar cell array during the startup process, so that the startup process is smoother.
  • the photovoltaic inverter circuit includes a first Boost converter, a second Boost converter, and an inverter group, the inverter group includes at least one five-level inverter, and FIG. 1 shows a photovoltaic inverse
  • FIG. 2 is a flow chart of a control method of a photovoltaic inverter circuit disclosed in the present invention.
  • the control method includes:
  • Step S1 After receiving the power-on command, charge the positive total bus capacitor and the negative total bus capacitor.
  • the inverter group can be turned on when the DC side voltage and the AC side voltage satisfy the grid connection condition and the inverter has no fault. Since the DC side voltage required for starting the five-level inverter is higher than the open circuit voltage of the solar array, the control device charges the positive total bus capacitor and the negative total bus capacitor after receiving the power-on command to establish The total bus start voltage.
  • Step S2 When the first preset condition is met, the charging operation is stopped, and the phase locked loop of the power grid is controlled to perform a phase lock operation.
  • the preset condition may be any one of the following: the total bus voltage reaches a first voltage threshold, the total bus voltage refers to a voltage between the positive total bus and the negative total bus; or, the positive total bus capacitance and the negative total bus capacitance are charged.
  • the time reaches the first time threshold. It should be noted here that the first time threshold is greater than or equal to the time required for the total bus voltage to reach the first voltage threshold. Wherein the first voltage threshold is slightly smaller
  • the line voltage peak on the AC side, and the AC side refers to the output of the filter circuit connected to the AC output of the five-level inverter.
  • the first voltage threshold can be set to the difference between the line voltage peak on the AC side and the system loss during charging.
  • the charging of the positive total bus capacitor and the negative total bus capacitor is stopped, and the phase locked loop in the power grid is controlled to perform a phase lock operation.
  • Step S3 After the phase-locked loop completes the phase-locking operation, the five-level inverter is started in the three-level mode, so that the output level of the five-level inverter is an electrical signal of V2Pos, 0, and -V2Neg, and five The level inverter performs voltage loop control and current loop control.
  • the AC output terminal AC of the five-level inverter can output electrical signals with level values of V2Pos, 0 and -V2Neg.
  • Step S4 When the second preset condition is met, voltage loop control is performed on the first Boost converter and the second Boost converter to control the first Boost converter and the second Boost converter to start at no load.
  • the second preset condition may be any one of the following: the total bus voltage reaches a set value; or the time that the five-level inverter operates in the three-level mode reaches a second time threshold, the second time threshold being greater than or Equal to the time required for the total bus voltage to reach the set value.
  • the set value is slightly lower than the sampled average value of the total bus voltage after the five-level inverter is started in the three-level mode and before the voltage-loop control is performed on the five-level inverter.
  • the set value is 98% to 99.5 of the average sample voltage of the total bus voltage after the five-level inverter is started in the three-level mode and before the voltage loop control is performed on the five-level inverter. %.
  • the Boost converter no-load start-up means that the load of the Boost converter is 0 or very low. Due to the fluctuation of the output voltage of the solar array, the input voltage of the Boost converter completely follows the output voltage of the solar array, which is ideal. There is usually a small difference between the input voltage of the converter and the output voltage of the solar array. At this time, the load of the Boost converter is very low, and the Boost converter is considered to be no-load start-up.
  • the first Boost converter and the second Boost converter are no-load-started, power disturbances to the solar array are minimized.
  • the first Boost converter can be controlled by setting the target voltage value of the voltage loop control of the first Boost converter and the second Boost converter to a value slightly lower than 1/2 of the open circuit voltage of the solar cell array.
  • the second Boost converter is started without load.
  • the target voltage value of the voltage loop control of the first Boost converter and the second Boost converter is set to 49% of the open circuit voltage of the solar cell array.
  • Step S5 After the input voltage and the input current of the first Boost converter and the second Boost converter are stabilized, the five-level inverter is controlled to operate in the five-level mode.
  • the input voltage of the first Boost converter and the second Boost converter is stable, that is, the input voltage of the first Boost converter and the second Boost converter changes less than the first value in the unit time, the first Boost converter and The input current of the second Boost converter is stable, that is, the input current of the first Boost converter and the second Boost converter is less than the second value in the unit time.
  • the control device After the input voltage and the input current of the first Boost converter and the second Boost converter are stabilized, the control device enables the switch P1A, the switch P1B, the switch N1A, and the switch N1B, in this case, a five-level The inverter is capable of outputting electrical signals having level values of V2Pos, V1Pos, 0, -V2Neg, and -V1Neg.
  • the switch P1A, the switch P1B, the switch N1A and the switch N1B are turned on, since the first Boost converter and the second Boost converter have started the voltage loop control, the disturbance to the input voltage of the solar array is higher. Small, the corresponding disturbance to the input power of the solar array is also small.
  • the control method of the photovoltaic inverter circuit disclosed in the invention starts the five-level inverter in the inverter group in a three-level mode, so that the output level values of the five-level inverter are V2Pos, 0 and -V2Neg
  • the electric signal since the switch tube connected to the positive input bus and the negative input bus in the five-level inverter does not operate, it does not disturb the input voltage and input power of the solar array; after that, the first Boost transform is controlled.
  • the no-load start of the second Boost converter minimizes the power disturbance caused by the solar array; when switching the five-level inverter to the five-level mode, due to the first Boost converter and the second Boost
  • the converter has started voltage loop control, so it can reduce the solar array
  • the disturbance caused by the input voltage can correspondingly reduce the power disturbance caused to the solar array.
  • the control method disclosed in the present invention can reduce the fluctuation of the input voltage and the input power of the solar cell array during the startup process of the photovoltaic inverter circuit, so that the startup process is smoother.
  • the pre-charging circuit can be used to charge the positive total bus capacitor and the negative total bus capacitor.
  • FIG. 4 is a schematic diagram of a specific application scenario of the photovoltaic inverter circuit shown in FIG. 1 .
  • the AC output terminals of the five-level inverters 301, 302, and 303 are connected to the filter circuit 400, and the filter circuit 400 filters and processes the electrical signals output from the five-level inverters 301, 302, and 303.
  • the step-up transformer 600 performs a boosting process and then transmits it to the AC grid.
  • the filter circuit 400 is specifically an LCL type filter.
  • the precharge circuit 500 shown in Figure 4 includes three charging branches.
  • the first charging branch includes a first controllable switch K1, a second controllable switch K2 and a first resistor R1.
  • the second controllable switch K2 is connected in series between the first phase of the AC power grid and the AC output terminal of the five-level inverter 301, and the first controllable switch K1 and the first resistor R1 are connected in series and then connected in parallel to the second controllable Both ends of the switch K2.
  • the second charging branch includes a third controllable switch K3, a fourth controllable switch K4, and a second resistor R2.
  • the fourth controllable switch K4 is connected in series between the second phase of the AC power grid and the AC output end of the five-level inverter 302, and the third controllable switch K3 and the second resistor R2 are connected in series and then connected in parallel to the fourth controllable Both ends of the switch K4.
  • the third charging branch includes a fifth controllable switch K5, a sixth controllable switch K6, and a third resistor R3.
  • the sixth controllable switch K6 is connected in series between the third phase of the AC power grid and the AC output end of the five-level inverter 303, and the fifth controllable switch K5 and the third resistor R3 are connected in series and then connected in parallel to the sixth controllable Both ends of the switch K6.
  • the first controllable switch K1 and the second controllable switch K2 in the first charging branch are in an off state
  • the third controllable switch K3 and the fourth controllable switch in the second charging branch K4 is in the off state
  • the fifth controllable switch K5 and the sixth controllable switch K6 in the third charging branch are in the off state.
  • the control device controls the first controllable switch K1, the third controllable switch K3, and The fifth controllable switch K5 is closed, and the AC grid charges the positive total bus capacitor C3 and the negative total bus capacitor C4 through the first resistor R1, the second resistor R2 and the third resistor R3, and the charging path is: AC grid-charging circuit- Filter circuit - diode in reverse parallel connection with switch P2 - positive total bus capacitor C3; AC grid - charging circuit - filter circuit - diode - negative total bus capacitor C4 in anti-parallel with switch N2.
  • the charging operation of the positive total bus capacitor C3 and the negative total bus capacitor C4 is stopped.
  • the second controllable switch K2, the fourth controllable switch K4 and the sixth controllable switch K6 are closed, and after a certain time delay, the first controllable switch K1 and the third controllable switch K3 are disconnected.
  • the method further includes: performing current loop control on the first Boost converter and the second Boost converter. That is to say, in the case where it is determined that the second preset condition is satisfied, voltage loop control and current loop control are performed on the first Boost converter and the second Boost converter.
  • the following steps may also be performed: performing MPPT (Maximum Power Point Tracking) control on the first Boost converter and the second Boost converter to enable the solar cell
  • MPPT Maximum Power Point Tracking
  • the applicant simulates the process of starting the photovoltaic inverter circuit based on the control mode disclosed in the present invention, and the simulation result is shown in FIG. 5.
  • the process of starting the photovoltaic inverter circuit based on the existing method starts the five-level inverter directly in five-level mode
  • the simulation result is shown in FIG. 6.
  • the first curve is the bridge arm voltage
  • the bridge arm voltage is the voltage at the AC output of the five-level inverter
  • the second curve is the total bus.
  • the third curve is the grid side bridge arm current
  • the grid side bridge arm current refers to the current output from the AC output of the five-level inverter to the filter circuit
  • the fourth curve is the input voltage of the solar array.
  • the fifth curve is the input current of the first Boost converter.
  • the target voltage value is slightly lower than 1/2 of the open circuit voltage of the solar array, and the input power is approximately 0; at time t2, the five-level inverter is switched from the three-level operation mode to the five-level operation mode; t2 ⁇ T3, the target voltage value of the voltage loop control continues to be maintained; at time t3, the MPPT control is started, and the startup process ends. It can be seen that the total bus voltage and the input voltage disturbance of the solar cell array are small during the startup process, the input power ripple is small, and the startup process is smooth.
  • the five-level inverter is started in a five-level mode; at time t1, the first Boost converter and the second Boost converter are started; at time t2, the MPPT control is started.
  • the output current is instantaneously zero due to the presence of the ripple of the five-level inverter, thereby causing the first Boost converter and the second Boost transform.
  • the device is equivalent to the load start, causing fluctuations in the input voltage and input power of the solar array, which in turn causes fluctuations in the total DC bus voltage.
  • the invention discloses a control method of a photovoltaic inverter circuit, and correspondingly, the invention also discloses a control device of a photovoltaic inverter circuit.
  • the photovoltaic inverter circuit includes a first Boost converter, a second Boost converter, and an inverter group, the inverter group includes at least one five-level inverter, and FIG. 1 shows a photovoltaic inverse The structure of the variable circuit in which the inverter group includes three five-level inverters.
  • FIG. 7 is a schematic structural diagram of a control device of a photovoltaic inverter circuit disclosed in the present invention.
  • the control device includes a first control unit 100, a second control unit 200, a third control unit 300, a fourth control unit 400, and a fifth control unit 500.
  • the first control unit 100 is configured to charge the positive total bus capacitor and the negative total bus capacitor after receiving the power-on command. Since the DC-side voltage required for starting the five-level inverter is higher than the open circuit voltage of the solar cell array, the first control unit 100 charges the positive total bus capacitor and the negative total bus capacitor after receiving the power-on command. To establish the total bus start voltage.
  • the second control unit 200 is configured to stop the charging operation when the first preset condition is met, and control the phase locked loop of the power grid to perform a phase locking operation.
  • the preset condition may be any one of the following: the total bus voltage reaches the first voltage threshold, the total bus The voltage is the voltage between the positive total bus and the negative total bus; or, the time to charge the positive total bus capacitance and the negative total bus capacitance reaches a first time threshold.
  • the first time threshold is greater than or equal to the time required for the total bus voltage to reach the first voltage threshold.
  • the first voltage threshold is slightly smaller than the line voltage peak on the AC side, and the AC side refers to the output end of the filter circuit connected to the AC output end of the five-level inverter.
  • the first voltage threshold can be set to the difference between the line voltage peak on the AC side and the system loss during charging.
  • the second control unit 200 has a different structure.
  • the second control unit 200 includes a first determining module, and the first determining module is configured to determine that the first preset condition is met when the total bus voltage reaches the first voltage threshold.
  • the second control unit 200 includes a second determining module, configured to determine that the first preset condition is met when the time for charging the positive total bus capacitor and the negative total bus capacitor reaches the first time threshold.
  • the third control unit 300 is configured to start the five-level inverter in a three-level mode after the phase-locked loop completes the phase-locking operation, so that the five-level inverter can output the level values of V2Pos, 0, and -V2Neg
  • the electrical signal is used for voltage loop control and current loop control of the five-level inverter.
  • the fourth control unit 400 performs voltage loop control on the first Boost converter and the second Boost converter to control the first Boost converter and the second Boost converter to start idle when the second preset condition is met.
  • the second preset condition may be any one of the following: the total bus voltage reaches a set value; or the time that the five-level inverter operates in the three-level mode reaches a second time threshold, the second time threshold being greater than or Equal to the time required for the total bus voltage to reach the set value.
  • the set value is slightly lower than the sampled average value of the total bus voltage after the five-level inverter is started in the three-level mode and before the voltage-loop control is performed on the five-level inverter.
  • the set value is 98% to 99.5 of the average sample voltage of the total bus voltage after the five-level inverter is started in the three-level mode and before the voltage loop control is performed on the five-level inverter. %.
  • the fourth control unit 400 has a different structure.
  • the fourth control unit 400 includes a third determining module, configured to determine that the second preset condition is met when the total bus voltage reaches a set value.
  • the fourth control unit 400 includes a fourth determining module, configured to determine that the second preset condition is met when the time that the five-level inverter is operating in the three-level mode reaches the second time threshold.
  • the fifth control unit 500 is configured to control the five-level inverter to operate in the five-level mode after the input voltage and the input current of the first Boost converter and the second Boost converter are stabilized.
  • the control device of the photovoltaic inverter circuit disclosed in the invention starts the five-level inverter in the inverter group in a three-level mode, so that the output level values of the five-level inverter are V2Pos, 0 and -V2Neg
  • the electric signal since the switch tube connected to the positive input bus and the negative input bus in the five-level inverter does not operate, it does not disturb the input voltage and input power of the solar array; after that, the first Boost transform is controlled.
  • the no-load start of the second Boost converter minimizes the power disturbance caused by the solar array; when switching the five-level inverter to the five-level mode, due to the first Boost converter and the second Boost
  • the converter has initiated voltage loop control, thereby reducing the disturbance to the input voltage of the solar array and correspondingly reducing the power disturbance to the solar array.
  • the control device disclosed in the present invention can reduce the fluctuation of the input voltage and the input power of the solar cell array during the startup of the photovoltaic inverter circuit, so that the startup process is smoother.
  • the sixth control unit 600 can be further disposed in the control device, as shown in FIG.
  • the sixth control unit 600 performs current loop control on the first Boost converter and the second Boost converter if the fourth control unit 400 determines that the second preset condition is satisfied.
  • the seventh control unit 700 may be further provided in the control device as shown in FIG.
  • the seventh control unit 700 is configured to perform MPPT maximum power point tracking control on the first Boost converter and the second Boost converter after the fifth control unit 500 controls the five-level inverter to operate in the five-level mode, Allows the solar array to output maximum power.

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Abstract

一种光伏逆变电路的控制方法及控制装置，该控制方法包括：在接收到开机指令后，对正总母线电容和负总母线电容充电（S1）；在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作（S2）；在锁相环完成锁相操作之后，以三电平模式启动五电平逆变器，对五电平逆变器进行电压环控制和电流环控制（S3）；在满足第二预设条件时，控制第一Boost变换器和第二Boost变换器空载启动，对第一Boost变换器和第二Boost变换器进行电压环控制（S4）；在第一Boost变换器和第二Boost变换器的输入电压和输入电流稳定后，控制五电平逆变器以五电平模式运行（S5）。该控制方法能够降低光伏逆变电路启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。

Description

光伏逆变电路的控制方法及控制装置
本申请要求于2014年6月30日提交中国专利局、申请号为201410309844.4、发明名称为“光伏逆变电路的控制方法及控制装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明属于光伏发电技术领域，尤其涉及光伏逆变电路的控制方法及控制装置。
背景技术
光伏发电技术目前已经得到广泛的应用。逆变器是光伏逆变电路中非常重要的部件。目前出现的五电平逆变器具有更低的并网电流纹波和更低的开关损耗，相较于传统的两电平或三电平逆变器具有更低的并网电流谐波失真和更高的效率。
图1为基于五电平逆变器构建的一种光伏逆变电路，主要包括第一Boost(升压)变换器201、第二Boost变换器202以及逆变器组，其中逆变器组包括三个五电平逆变器301、302和303。太阳能电池阵列100接入正输入母线和负输入母线，正输入母线相对于中点的电压为V1Pos，中点相对于负输入母线的电压为V1Neg。正输入母线电压经过第一Boost变换器201升压得到正总母线电压，负输入母线电压经过第二Boost变换器202升压得到负总母线电压，正总母线相对于中点的电压为V2Pos，中点相对于负总母线的电压为V2Neg。五电平逆变器301、302和303能够输出电平值为V2Pos、V1Pos、0、-V1Neg和-V2Neg的电信号。在图1中，C1为正输入母线电容，C2为负输入母线电容，C3为正总母线电容，C4为负总母线电容。这里需要说明的是，当光伏逆变电路的类型不同时，其逆变器组所包含的五电平逆变器的数量也不同，例如：单相光伏逆变电路的逆变器组仅包括一个五电平逆变器，两相光伏逆变电路的逆变器组包括两个五电平逆变器。也就是说，光伏逆变电路的逆变器组至少包括一个五电平逆变器。另外，五电平逆变器的结构并不限定于图1所示，采用其他结构的五电平逆变器也是可以的。
目前，在启动光伏逆变电路的过程中，直接以五电平模式启动五电平逆变器，导致太阳能电池阵列的输入电压和输入功率存在较大的波动，启动过程不平稳。
发明内容
有鉴于此，本发明实施例的目的在于提供一种光伏逆变电路的控制方法和控制装置，以降低启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。
为实现上述目的，本发明提供如下技术方案：
一种光伏逆变电路的控制方法，所述光伏逆变电路包括第一Boost升压变换器、第二Boost变换器以及逆变器组，所述逆变器组包括至少一个五电平逆变器，所述控制方法包括：
在接收到开机指令后，对正总母线电容和负总母线电容充电；
在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作；
在所述锁相环完成锁相操作之后，以三电平模式启动所述五电平逆变器，使得所述五电平逆变器能够输出电平值为V2Pos、0和-V2Neg的电信号，对所述五电平逆变器进行电压环控制和电流环控制；
在满足第二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电压环控制，以控制所述第一Boost变换器和所述第二Boost变换器空载启动；
在所述第一Boost变换器和所述第二Boost变换器的输入电压和输入电流稳定后，控制所述五电平逆变器以五电平模式运行。
优选的，在上述控制方法中，所述第一预设条件包括以下任意一种：总母线电压达到第一电压阈值；或者，对所述正总母线电容和所述负总母线电容充电的时间达到第一时间阈值。
优选的，在上述控制方法中，所述第二预设条件包括以下任意一种：总母线电压达到设定值；或者，所述五电平逆变器以三电平模式运行的时间达到第二时间阈值。
优选的，在上述控制方法中，在满足第二预设条件时，还包括：对所述第一Boost变换器和所述第二Boost变换器进行电流环控制。
优选的，在上述控制方法中，在控制所述五电平逆变器以五电平模式运行之后，还包括：对所述第一Boost变换器和所述第二Boost变换器进行MPPT最大功率点追踪控制，以使得所述太阳能电池阵列输出最大功率。
本发明还公开一种光伏逆变电路的控制装置，所述光伏逆变电路包括第一Boost升压变换器、第二Boost变换器以及逆变器组，所述逆变器组包括至少一个五电平逆变器，所述控制装置包括：
第一控制单元，用于在接收到开机指令后，对正总母线电容和负总母线电容充电；
第二控制单元，用于在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作；
第三控制单元，用于在所述锁相环完成锁相操作之后，以三电平模式启动所述五电平逆变器，使得所述五电平逆变器能够输出电平值为V2Pos、0和-V2Neg的电信号，对所述五电平逆变器进行电压环控制和电流环控制；
第四控制单元，在满足第二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电压环控制，以控制所述第一Boost变换器和所述第二Boost变换器空载启动；
第五控制单元，用于在所述第一Boost变换器和所述第二Boost变换器的输入电压和输入电流稳定后，控制所述五电平逆变器以五电平模式运行。
优选的，在上述控制装置中，所述第二控制单元包括第一判断模块或者第二判断模块；所述第一判断模块用于在所述总母线电压达到第一电压阈值时，确定满足第一预设条件；所述第二判断模块用于在对所述正总母线电容和所述负总母线电容充电的时间达到第一时间阈值时，确定满足第一预设条件。
优选的，在上述控制装置中，所述第四控制单元包括第三判断模块或第四判断模块；所述第三判断模块用于在总母线电压达到设定值时，确定满足第二预设条件；所述第四判断模块用于在所述五电平逆变器以三电平模式运行的时间达到第二时间阈值时，确定满足第二预设条件。
优选的，上述控制装置还包括第六控制单元；所述第六控制单元在满足第 二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电流环控制。
优选的，上述控制装置还包括第七控制单元；所述第七控制单元用于在所述第五控制单元控制所述五电平逆变器以五电平模式运行之后，对所述第一Boost变换器和所述第二Boost变换器进行MPPT最大功率点追踪控制，以使得所述太阳能电池阵列输出最大功率。
由此可见，本发明的有益效果为：本发明公开的光伏逆变电路的控制方法，以三电平模式启动逆变器组中的五电平逆变器，使得五电平逆变器输出电平值为V2Pos、0和-V2Neg的电信号，由于五电平逆变器中与正输入母线和负输入母线连接的开关管均不动作，因此不会对太阳能电池阵列的输入电压和输入功率造成扰动；之后，控制第一Boost变换器和第二Boost变换器空载启动，将对太阳能电池阵列造成的功率扰动降至最低；在将五电平逆变器切换至五电平模式时，由于第一Boost变换器和第二Boost变换器已经启动电压环控制，因此可以降低对太阳能电池阵列的输入电压造成的扰动，相应的可以降低对太阳能电池阵列造成的功率扰动。与现有方式相比，基于本发明公开的控制方法，能够降低光伏逆变电路启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1为现有的一种光伏逆变电路的结构示意图；
图2为本发明公开的光伏逆变电路的一种控制方法的流程图；
图3为一种五电平逆变器拓扑的结构示意图；
图4为图1所示光伏逆变电路的一种具体应用场景示意图；
图5为对基于本发明公开的控制方法启动光伏逆变电路的过程进行仿真 获得的波形图；
图6为对基于现有方式启动光伏逆变电路的过程进行仿真获得的波形图；
图7为本发明公开的光伏逆变电路的一种控制装置的结构示意图；
图8为本发明公开的光伏逆变电路的另一种控制装置的结构示意图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明公开一种光伏逆变电路的控制方法，以降低启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。在本发明中，光伏逆变电路包括第一Boost变换器、第二Boost变换器以及逆变器组，逆变器组包括至少一个五电平逆变器，图1示出了一种光伏逆变电路的结构，其中逆变器组包括三个五电平逆变器。
参见图2，图2为本发明公开的光伏逆变电路的一种控制方法的流程图。该控制方法包括：
步骤S1：在接收到开机指令后，对正总母线电容和负总母线电容充电。
在直流侧电压和交流侧电压均满足并网条件，且逆变器无故障的情况下就可以开启逆变器组。由于五电平逆变器启动所需的直流侧电压高于太阳能电池阵列的开路电压，因此控制装置在接收到开机指令后，要对正总母线电容和负总母线电容进行充电处理，以建立总母线启动电压。
步骤S2：在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作。
该预设条件可以为以下任意一种：总母线电压达到第一电压阈值，总母线电压是指正总母线和负总母线之间的电压；或者，对正总母线电容和负总母线电容充电的时间达到第一时间阈值。这里需要说明的是，该第一时间阈值大于或等于总母线电压达到第一电压阈值所需的时间。其中，第一电压阈值略小于 交流侧的线电压峰值，交流侧指的是与五电平逆变器的交流输出端连接的滤波电路的输出端。实施中，第一电压阈值可以设置为交流侧的线电压峰值与充电过程中的系统损耗的差值。
在对正总母线电容和负总母线电容充电过程中，判断是否满足第一预设条件。当确定满足第一预设条件时，停止为正总母线电容和负总母线电容继续充电，控制电网中的锁相环启动，进行锁相操作。
步骤S3：在锁相环完成锁相操作之后，以三电平模式启动五电平逆变器，使得五电平逆变器输出电平值为V2Pos、0和-V2Neg的电信号，对五电平逆变器进行电压环控制和电流环控制。
这里结合图3对以三电平模式启动五电平逆变器的过程进行说明。在图3所示的五电平逆变器中，仅开关管P2、开关管N2、开关管P0A和开关管P0B工作，而开关管P1A、开关管P1B、开关管N1A和开关管N1B均不动作，在这种情况下，五电平逆变器的交流输出端AC能够输出电平值为V2Pos、0和-V2Neg的电信号。在以三电平模式启动五电平逆变器的过程中，由于五电平逆变器中与正输入母线和负输入母线连接的开关管(开关管P1A、开关管P1B、开关管N1A和开关管N1B)均不动作，因此不会对太阳能电池阵列的输入电压和输入功率造成扰动。
步骤S4：在满足第二预设条件时，对第一Boost变换器和第二Boost变换器进行电压环控制，以控制第一Boost变换器和第二Boost变换器空载启动。
该第二预设条件可以为以下任意一种：总母线电压达到设定值；或者，五电平逆变器以三电平模式运行的时间达到第二时间阈值，该第二时间阈值大于或等于总母线电压达到设定值所需的时间。其中，该设定值略低于在以三电平模式启动五电平逆变器之后、且在对五电平逆变器进行电压环控制之前，总母线电压的采样平均值。例如，该设定值为：在以三电平模式启动五电平逆变器之后、且在对五电平逆变器进行电压环控制之前，总母线电压的采样平均值的98％～99.5％。
这里需要说明的是：在本技术领域，Boost变换器空载启动指的是Boost变换器的负载为0或者很低。由于太阳能电池阵列的输出电压存在波动，Boost变换器的输入电压完全跟随太阳能电池阵列的输出电压是理想情况，Boost 变换器的输入电压与太阳能电池阵列的输出电压通常会存在很小的差异，此时Boost变换器的负载很低，也认为Boost变换器为空载启动。
由于第一Boost变换器和第二Boost变换器是空载启动的，因此将对太阳能电池阵列造成的功率扰动降至最低。实施中，将第一Boost变换器和第二Boost变换器的电压环控制的目标电压值设定为略低于太阳能电池阵列的开路电压的1/2的数值，就可以控制第一Boost变换器和第二Boost变换器空载启动。例如：将第一Boost变换器和第二Boost变换器的电压环控制的目标电压值设定为太阳能电池阵列的开路电压的49％。
步骤S5：在第一Boost变换器和第二Boost变换器的输入电压和输入电流稳定后，控制五电平逆变器以五电平模式运行。
第一Boost变换器和第二Boost变换器的输入电压稳定，是指第一Boost变换器和第二Boost变换器的输入电压在单位时间内的变化量小于第一数值，第一Boost变换器和第二Boost变换器的输入电流稳定，是指第一Boost变换器和第二Boost变换器的输入电流在单位时间内的变化量小于第二数值。
这里仍结合图3对控制五电平逆变器以五电平模式运行进行说明。在第一Boost变换器和第二Boost变换器的输入电压和输入电流稳定之后，控制装置使能开关管P1A、开关管P1B、开关管N1A和开关管N1B，在这种情况下，五电平逆变器能够输出电平值为V2Pos、V1Pos、0、-V2Neg和-V1Neg的电信号。在开关管P1A、开关管P1B、开关管N1A和开关管N1B开通的时刻，由于第一Boost变换器和第二Boost变换器已经启动电压环控制，因此对太阳能电池阵列的输入电压造成的扰动较小，相应的对太阳能电池阵列的输入功率的造成的扰动也较小。
本发明公开的光伏逆变电路的控制方法，以三电平模式启动逆变器组中的五电平逆变器，使得五电平逆变器输出电平值为V2Pos、0和-V2Neg的电信号，由于五电平逆变器中与正输入母线和负输入母线连接的开关管均不动作，因此不会对太阳能电池阵列的输入电压和输入功率造成扰动；之后，控制第一Boost变换器和第二Boost变换器空载启动，将对太阳能电池阵列造成的功率扰动降至最低；在将五电平逆变器切换至五电平模式时，由于第一Boost变换器和第二Boost变换器已经启动电压环控制，因此可以降低对太阳能电池阵列 的输入电压造成的扰动，相应的可以降低对太阳能电池阵列造成的功率扰动。与现有方式相比，基于本发明公开的控制方法，能够降低光伏逆变电路启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。
实施中，可以采用预充电电路对正总母线电容和负总母线电容进行充电处理。
这里结合图4进行说明，图4为图1所示光伏逆变电路的一种具体应用场景示意图。在图4中，五电平逆变器301、302和303的交流输出端与滤波电路400连接，滤波电路400对五电平逆变器301、302和303输出的电信号进行滤波处理后送入升压变压器600进行升压处理，之后传输至交流电网。滤波电路400具体为LCL型滤波器。图4中所示的预充电电路500包括三个充电支路。
第一充电支路包括第一可控开关K1、第二可控开关K2和第一电阻R1。其中，第二可控开关K2串联在交流电网的第一相和五电平逆变器301的交流输出端之间，第一可控开关K1和第一电阻R1串联之后并联在第二可控开关K2的两端。
第二充电支路包括第三可控开关K3、第四可控开关K4和第二电阻R2。其中，第四可控开关K4串联在交流电网的第二相和五电平逆变器302的交流输出端之间，第三可控开关K3和第二电阻R2串联之后并联在第四可控开关K4的两端。
第三充电支路包括第五可控开关K5、第六可控开关K6和第三电阻R3。其中，第六可控开关K6串联在交流电网的第三相和五电平逆变器303的交流输出端之间，第五可控开关K5和第三电阻R3串联之后并联在第六可控开关K6的两端。
在启动充电操作之前，第一充电支路中的第一可控开关K1和第二可控开关K2处于断开状态，第二充电支路中的第三可控开关K3和第四可控开关K4处于断开状态，第三充电支路中的第五可控开关K5和第六可控开关K6处于断开状态。此时，五电平逆变器301、302和303与交流电网之间没有连接。在接收到开机指令后，控制装置控制第一可控开关K1、第三可控开关K3和 第五可控开关K5闭合，交流电网通过第一电阻R1、第二电阻R2和第三电阻R3对正总母线电容C3和负总母线电容C4进行充电，充电路径为：交流电网-充电电路-滤波电路-与开关管P2反向并联的二极管-正总母线电容C3；交流电网-充电电路-滤波电路-与开关管N2反向并联的二极管-负总母线电容C4。
当满足第一预设条件时，要停止对正总母线电容C3和负总母线电容C4的充电操作。此时，首先闭合第二可控开关K2、第四可控开关K4和第六可控开关K6，在延时特定时间后，再断开第一可控开关K1、第三可控开关K3和第五可控开关K5。
作为优选方式，在确定满足第二预设条件的情况下，还包括：对第一Boost变换器和第二Boost变换器进行电流环控制。也就是说，在确定满足第二预设条件的情况下，对第一Boost变换器和第二Boost变换器进行电压环控制和电流环控制。通过增加对第一Boost变换器和第二Boost变换器的电流环控制，能够提高光伏逆变电路的动态响应的速度。
另外，在控制五电平逆变器以五电平模式运行之后，还可以执行以下步骤：对第一Boost变换器和第二Boost变换器进行MPPT(最大功率点追踪)控制，以使得太阳能电池阵列输出最大功率。
申请人对基于本发明公开的控制方式启动光伏逆变电路的过程进行仿真，仿真结果如图5所示。同时，对基于现有方式(直接以五电平模式启动五电平逆变器)启动光伏逆变电路的过程进行仿真，仿真结果如图6所示。在图5和图6中，按照从上到下的顺序，第一条曲线为桥臂电压，桥臂电压指的是五电平逆变器的交流输出端的电压，第二条曲线为总母线电压，第三条曲线为网侧桥臂电流，网侧桥臂电流指的是五电平逆变器的交流输出端输出到滤波电路的电流，第四条曲线为太阳能电池阵列的输入电压，第五条曲线为第一Boost变换器的输入电流。
在图5中，t0时刻，正总母线电容和负总母线电容的预充电结束，电网锁相完成，五电平逆变器按照三电平模式启动；t0～t1，总母线电压由预充电电压 值缓慢爬升至设定值；t1时刻，第一Boost变换器和第二Boost变换器启动；t1～t2，对第一Boost变换器和第二Boost变换器进行电压环控制，并且电压环控制的目标电压值略低于太阳能电池阵列的开路电压的1/2，此时输入功率近似为0；t2时刻，五电平逆变器由三电平工作模式切换至五电平工作模式；t2～t3，电压环控制的目标电压值继续保持；t3时刻，启动MPPT控制，启动过程结束。可见，启动过程中总母线电压和太阳能电池阵列的输入电压扰动均较小，输入功率脉动很小，启动过程平滑。
在图6中，t0时刻，五电平逆变器以五电平模式启动；t1时刻，第一Boost变换器和第二Boost变换器启动；t2时刻，启动MPPT控制。可以看到，当第一Boost变换器和第二Boost变换器启动时，由于五电平逆变器纹波的存在导致输出电流瞬时不为0，从而造成第一Boost变换器和第二Boost变换器相当于带载启动，造成太阳能电池阵列的输入电压和输入功率出现波动，进而引起总直流母线电压的波动。
本发明上述公开了光伏逆变电路的控制方法，相应的，本发明还公开光伏逆变电路的控制装置。在本发明中，光伏逆变电路包括第一Boost变换器、第二Boost变换器以及逆变器组，逆变器组包括至少一个五电平逆变器，图1示出了一种光伏逆变电路的结构，其中逆变器组包括三个五电平逆变器。
参见图7，图7为本发明公开的光伏逆变电路的一种控制装置的结构示意图。该控制装置包括第一控制单元100、第二控制单元200、第三控制单元300、第四控制单元400和第五控制单元500。
其中：
第一控制单元100，用于在接收到开机指令后，对正总母线电容和负总母线电容充电。由于五电平逆变器启动所需的直流侧电压高于太阳能电池阵列的开路电压，因此第一控制单元100在接收到开机指令后，要对正总母线电容和负总母线电容进行充电处理，以建立总母线启动电压。
第二控制单元200，用于在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作。
该预设条件可以为以下任意一种：总母线电压达到第一电压阈值，总母线 电压是指正总母线和负总母线之间的电压；或者，对正总母线电容和负总母线电容充电的时间达到第一时间阈值。这里需要说明的是，该第一时间阈值大于或等于总母线电压达到第一电压阈值所需的时间。其中，第一电压阈值略小于交流侧的线电压峰值，交流侧指的是与五电平逆变器的交流输出端连接的滤波电路的输出端。实施中，第一电压阈值可以设置为交流侧的线电压峰值与充电过程中的系统损耗的差值。
相应的，第二控制单元200具有不同的结构。
例如：第二控制单元200包括第一判断模块，该第一判断模块用于在总母线电压达到第一电压阈值时，确定满足第一预设条件。或者，第二控制单元200包括第二判断模块，该第二判断模块用于在对正总母线电容和负总母线电容充电的时间达到第一时间阈值时，确定满足第一预设条件。
第三控制单元300，用于在锁相环完成锁相操作之后，以三电平模式启动五电平逆变器，使得五电平逆变器能够输出电平值为V2Pos、0和-V2Neg的电信号，对五电平逆变器进行电压环控制和电流环控制。
第四控制单元400，在满足第二预设条件时，对第一Boost变换器和第二Boost变换器进行电压环控制，以控制第一Boost变换器和第二Boost变换器空载启动,。
该第二预设条件可以为以下任意一种：总母线电压达到设定值；或者，五电平逆变器以三电平模式运行的时间达到第二时间阈值，该第二时间阈值大于或等于总母线电压达到设定值所需的时间。其中，该设定值略低于在以三电平模式启动五电平逆变器之后、且在对五电平逆变器进行电压环控制之前，总母线电压的采样平均值。例如，该设定值为：在以三电平模式启动五电平逆变器之后、且在对五电平逆变器进行电压环控制之前，总母线电压的采样平均值的98％～99.5％。
相应的，第四控制单元400具有不同的结构。
例如：第四控制单元400包括第三判断模块，该第三判断模块用于在总母线电压达到设定值时，确定满足第二预设条件。或者，第四控制单元400包括第四判断模块，该第四判断模块用于在五电平逆变器以三电平模式运行的时间达到第二时间阈值时，确定满足第二预设条件。
第五控制单元500，用于在第一Boost变换器和第二Boost变换器的输入电压和输入电流稳定后，控制五电平逆变器以五电平模式运行。
本发明公开的光伏逆变电路的控制装置，以三电平模式启动逆变器组中的五电平逆变器，使得五电平逆变器输出电平值为V2Pos、0和-V2Neg的电信号，由于五电平逆变器中与正输入母线和负输入母线连接的开关管均不动作，因此不会对太阳能电池阵列的输入电压和输入功率造成扰动；之后，控制第一Boost变换器和第二Boost变换器空载启动，将对太阳能电池阵列造成的功率扰动降至最低；在将五电平逆变器切换至五电平模式时，由于第一Boost变换器和第二Boost变换器已经启动电压环控制，因此可以降低对太阳能电池阵列的输入电压造成的扰动，相应的可以降低对太阳能电池阵列造成的功率扰动。与现有方式相比，基于本发明公开的控制装置，能够降低光伏逆变电路启动过程中太阳能电池阵列的输入电压和输入功率的波动，使得启动过程更为平滑。
实施中，可以在控制装置中进一步设置第六控制单元600，如图8所示。该第六控制单元600在第四控制单元400确定满足第二预设条件的情况下，对第一Boost变换器和第二Boost变换器进行电流环控制。
另外，还可以在控制装置中进一步设置第七控制单元700，如图8所示。该第七控制单元700用于在第五控制单元500控制五电平逆变器以五电平模式运行之后，对第一Boost变换器和第二Boost变换器进行MPPT最大功率点追踪控制，以使得太阳能电池阵列输出最大功率。
最后，还需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的装置而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种光伏逆变电路的控制方法，所述光伏逆变电路包括第一Boost升压变换器、第二Boost变换器以及逆变器组，所述逆变器组包括至少一个五电平逆变器，其特征在于，所述控制方法包括：
    在接收到开机指令后，对正总母线电容和负总母线电容充电；
    在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作；
    在所述锁相环完成锁相操作之后，以三电平模式启动所述五电平逆变器，使得所述五电平逆变器能够输出电平值为V2Pos、0和-V2Neg的电信号，对所述五电平逆变器进行电压环控制和电流环控制；
    在满足第二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电压环控制，以控制所述第一Boost变换器和所述第二Boost变换器空载启动；
    在所述第一Boost变换器和所述第二Boost变换器的输入电压和输入电流稳定后，控制所述五电平逆变器以五电平模式运行。
  2. 根据权利要求1所述的控制方法，其特征在于，所述第一预设条件包括以下任意一种：
    总母线电压达到第一电压阈值；
    或者，对所述正总母线电容和所述负总母线电容充电的时间达到第一时间阈值。
  3. 根据权利要求1或2所述的控制方法，其特征在于，所述第二预设条件包括以下任意一种：
    总母线电压达到设定值；
    或者，所述五电平逆变器以三电平模式运行的时间达到第二时间阈值。
  4. 根据权利要求3所述的控制方法，其特征在于，在满足第二预设条件时，还包括：
    对所述第一Boost变换器和所述第二Boost变换器进行电流环控制。
  5. 根据权利要求4所述的控制方法，其特征在于，在控制所述五电平逆变器以五电平模式运行之后，还包括：
    对所述第一Boost变换器和所述第二Boost变换器进行MPPT最大功率点追踪控制，以使得所述太阳能电池阵列输出最大功率。
  6. 一种光伏逆变电路的控制装置，所述光伏逆变电路包括第一Boost升压变换器、第二Boost变换器以及逆变器组，所述逆变器组包括至少一个五电平逆变器，其特征在于，所述控制装置包括：
    第一控制单元，用于在接收到开机指令后，对正总母线电容和负总母线电容充电；
    第二控制单元，用于在满足第一预设条件时，停止充电操作，控制电网的锁相环进行锁相操作；
    第三控制单元，用于在所述锁相环完成锁相操作之后，以三电平模式启动所述五电平逆变器，使得所述五电平逆变器能够输出电平值为V2Pos、0和-V2Neg的电信号，对所述五电平逆变器进行电压环控制和电流环控制；
    第四控制单元，在满足第二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电压环控制，以控制所述第一Boost变换器和所述第二Boost变换器空载启动；
    第五控制单元，用于在所述第一Boost变换器和所述第二Boost变换器的输入电压和输入电流稳定后，控制所述五电平逆变器以五电平模式运行。
  7. 根据权利要求6所述的控制装置，其特征在于，所述第二控制单元包括第一判断模块或者第二判断模块；
    所述第一判断模块用于在所述总母线电压达到第一电压阈值时，确定满足第一预设条件；
    所述第二判断模块用于在对所述正总母线电容和所述负总母线电容充电的时间达到第一时间阈值时，确定满足第一预设条件。
  8. 根据权利要求6或7所述的控制装置，其特征在于，所述第四控制单元包括第三判断模块或第四判断模块；
    所述第三判断模块用于在总母线电压达到设定值时，确定满足第二预设条件；
    所述第四判断模块用于在所述五电平逆变器以三电平模式运行的时间达到第二时间阈值时，确定满足第二预设条件。
  9. 根据权利要求8所述的控制装置，其特征在于，还包括第六控制单元；
    所述第六控制单元在满足第二预设条件时，对所述第一Boost变换器和所述第二Boost变换器进行电流环控制。
  10. 根据权利要求9所述的控制装置，其特征在于，还包括第七控制单元；
    所述第七控制单元用于在所述第五控制单元控制所述五电平逆变器以五电平模式运行之后，对所述第一Boost变换器和所述第二Boost变换器进行MPPT最大功率点追踪控制，以使得所述太阳能电池阵列输出最大功率。
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CN109103979A (zh) * 2018-10-24 2018-12-28 珠海格力电器股份有限公司 光伏用电设备及其充电控制方法、装置和电路、存储介质
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