WO2022227697A1 - 并网变流器的控制方法、装置及并网变流器 - Google Patents
并网变流器的控制方法、装置及并网变流器 Download PDFInfo
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- WO2022227697A1 WO2022227697A1 PCT/CN2022/070989 CN2022070989W WO2022227697A1 WO 2022227697 A1 WO2022227697 A1 WO 2022227697A1 CN 2022070989 W CN2022070989 W CN 2022070989W WO 2022227697 A1 WO2022227697 A1 WO 2022227697A1
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- 238000004364 calculation method Methods 0.000 claims description 26
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- 238000000605 extraction Methods 0.000 claims description 6
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- 238000005859 coupling reaction Methods 0.000 description 3
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Classifications
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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
- H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- 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 application belongs to the technical field of circuit control, and in particular relates to a control method and device of a grid-connected converter and a grid-connected converter.
- Photovoltaic converter is a key component in photovoltaic power generation system, which is a power converter that converts one form of electrical energy into another form of electrical energy.
- the grid-connected converter of the distributed power source will increase the outlet current on the grid side, and an excessively high current may trigger the overcurrent protection mechanism of the converter to act and disconnect from the grid.
- the random disconnection of grid-connected converters from the grid can easily lead to grid fluctuations, and even cause power system oscillations in severe cases, causing damage to the grid.
- the operation control strategy of photovoltaic grid-connected converters to deal with abnormal fluctuations in grid voltage is mainly to calculate accurate current commands by establishing a mathematical model of grid-connected converters with LCL filters.
- the low-voltage ride-through capability of the converter is still low, and it is difficult to ensure the stable ride-through of the grid-connected converter in the case of abnormal grid voltage.
- the embodiments of the present application provide a control method, device and grid-connected converter for a grid-connected converter, so as to solve the problem that the low-voltage ride-through capability of the grid-connected converter in the prior art is low.
- the first aspect of the embodiments of the present application provides a control method for a grid-connected converter, including:
- the step of judging the low voltage ride through if the output voltage is less than the preset voltage value, control the grid-connected converter to execute the low voltage ride through mode;
- Active component extraction step in the low voltage ride-through mode, calculating the positive-sequence active component and the negative-sequence active component of the output voltage;
- Drop depth calculation step according to the positive-sequence active component, negative-sequence active component and the rated voltage of the output voltage, calculate the voltage drop depth;
- the first reactive current reference value calculation step calculating the first reactive current reference value according to the voltage drop depth
- the first PWM signal generation step calculating a first PWM signal according to the first reactive current reference value and the output current, and the first PWM signal is used to control the grid-connected transformer in the low voltage ride-through mode. streamer.
- a second aspect of the embodiments of the present application provides a control device for a grid-connected converter, including:
- the acquisition module is used to acquire the output voltage, output current and rated voltage of the grid-connected converter
- a low-voltage ride-through judging module for judging that if the output voltage is less than a preset voltage value, then controlling the grid-connected converter to execute a low-voltage ride-through mode
- an active component extraction module configured to calculate the positive-sequence active component and the negative-sequence active component of the output voltage in the low-voltage ride-through mode
- a drop depth calculation module used for calculating the voltage drop depth according to the positive-sequence active component, the negative-sequence active component and the rated voltage of the output voltage
- a first reactive current reference value calculation module configured to calculate the first reactive current reference value according to the voltage drop depth
- a first PWM signal generation module configured to calculate a first PWM signal according to the first reactive current reference value and the output current, where the first PWM signal is used to control the parallel connection in the low voltage ride-through mode network converter.
- a third aspect of the embodiments of the present application provides a grid-connected converter, including a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the The computer program realizes the steps of the control method of the grid-connected converter as described above.
- a fourth aspect of the embodiments of the present application provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, realizes the control of the grid-connected converter as described above steps of the method.
- the embodiment of the present application has the beneficial effect that the control method of the grid-connected converter provided by the present embodiment firstly determines the output voltage, and if the output voltage is less than the preset voltage value, the grid-connected converter is controlled.
- the current transformer executes the low-voltage ride-through mode; and in the low-voltage ride-through mode, the positive-sequence active component and the negative-sequence active component of the output voltage are calculated; according to the positive-sequence active component, the negative-sequence active component and the rated voltage of the output voltage, the voltage drop is calculated. depth; finally calculate the first reactive current reference value according to the voltage drop depth; calculate the first PWM signal according to the first reactive current reference value and the output current.
- the voltage dip depth is calculated by the positive sequence component and the negative sequence component of the output voltage in the low voltage ride-through control, which can improve the low voltage ride-through capability of the grid-connected converter and ensure the stability of the grid-connected converter under abnormal output voltage conditions. cross.
- FIG. 1 is a schematic flowchart of a control method for a grid-connected converter provided by an embodiment of the present application
- FIG. 2 is a schematic circuit diagram of a grid-connected converter provided by an embodiment of the present application.
- FIG. 3 is a control block diagram of a grid-connected converter provided by an embodiment of the present application.
- FIG. 4 is a calculation block diagram of a first reactive current reference value provided by an embodiment of the present application.
- FIG. 5 is a schematic structural diagram of a control device for a grid-connected converter provided by an embodiment of the present application
- FIG. 6 is a schematic diagram of a grid-connected converter provided by an embodiment of the present application.
- FIG. 1 shows the implementation process of the control method for the grid-connected converter provided in this embodiment, and the control method for the grid-connected converter includes:
- FIG. 2 which shows a circuit diagram of a grid-connected converter, wherein the output voltage of the grid-connected converter is three-phase output voltages u ga , u gb and u gc , and the output current is are the three-phase output currents i ga , i gb and i gc .
- the executive body of this embodiment is a controller connected to the grid-connected converter and used to control the grid-connected converter.
- the preset voltage value is 0.9 times the rated voltage.
- the grid-connected converter enters the low voltage ride-through mode, and when the output voltage is greater than or equal to the preset voltage value, the grid-connected converter works in the normal working mode.
- S103 In the low-voltage ride-through mode, calculate the positive-sequence active component and the negative-sequence active component of the output voltage.
- Clark transform is first performed on the three-phase output voltages u ga , u gb and u gc to obtain u a and u b , and then Park transform is performed on u a and u b to obtain the positive sequence active component of the output voltage and negative sequence active components .
- S104 Calculate the voltage drop depth according to the positive-sequence active component, negative-sequence active component and rated voltage of the output voltage;
- S105 Calculate the first reactive current reference value according to the voltage drop depth
- S106 Calculate a first PWM signal according to the first reactive current reference value and the output current, where the first PWM signal is used to control the grid-connected converter in the low voltage ride-through mode.
- the PWM signal refers to the pulse width modulation signal (PWM, the English full name is Pulse width modulation).
- the evaluation criteria for the low voltage ride-through capability mainly include: the ride-through duration of the grid-connected converter and the ability to provide reactive power support.
- the medium and high voltage grid-connected certification standard VDE4110 issued by the German Electrotechnical Commission in 2018 stipulates the ride-through duration and the provision of reactive support power.
- this embodiment provides a control method for a grid-connected converter , the specific process is as follows:
- U p represents the positive sequence voltage amplitude of the output voltage
- U n represents the negative sequence voltage amplitude of the output voltage
- ⁇ p represents the positive sequence voltage phase angle
- ⁇ n represents the negative sequence voltage phase horn.
- I p represents the positive sequence current amplitude of the output current
- In represents the negative sequence current amplitude of the output current
- ⁇ 1 represents the phase angle of the positive sequence current relative to the positive sequence voltage
- ⁇ 2 represents the phase angle of the negative sequence current relative to the negative sequence voltage horn.
- the power delivered by the grid-connected converter to the grid is:
- Equation (7) gives the method to obtain the given value of output current by given active power, reactive power and output voltage.
- this embodiment describes the grid voltage sag depth through the voltage sag depth.
- the active power P 0 and the reactive power Q 0 are difficult to accurate description, so according to equation (7), the output current is further described as:
- Equation (11) gives the linear relationship between the output current reference value on the grid side and the voltage dip depth, and it can be seen from equation (11) that when calculating the output current reference value in this embodiment, not only the voltage dip It also considers the positive sequence component and negative sequence component of the output voltage at the same time, so as to avoid the problem of poor low voltage ride-through capability caused by unified control of each phase when the three-phase drop is unbalanced.
- the control method of the grid-connected converter provided in this embodiment firstly determines the magnitude of the output voltage, and if the output voltage is less than the preset voltage value, the grid-connected converter is controlled to execute the low-voltage ride-through mode; In low-voltage ride-through mode, the positive-sequence active component and negative-sequence active component of the output voltage are calculated; the voltage sag depth is calculated according to the positive-sequence active component, negative-sequence active component and rated voltage of the output voltage; finally, the first Reactive current reference value; calculate the first PWM signal according to the first reactive current reference value and the output current.
- the output current reference value is calculated by considering both the positive component and the negative sequence component of the output voltage in the low-voltage ride-through control, so that the low-voltage ride-through capability of the grid-connected converter can be improved, and the grid-connected converter can be guaranteed when the output voltage is abnormal. stable crossing.
- control method provided by this embodiment further includes:
- S202 In the normal working mode, calculate a second PWM signal according to the output current and the current given value, and the second PWM signal is used to control the grid-connected converter in the normal working mode.
- FIG. 3 shows a control block diagram of the grid-connected converter provided in this embodiment. Specifically, in the normal working mode, first, the output current and the current given value are All are converted from the abc coordinate system to the dq coordinate system, and then, the active component I d and the reactive component I q of the output current are calculated, and the active component I dr and the reactive component I qr of the current given value are calculated.
- S104 in FIG. 1 includes:
- S105 in FIG. 1 includes:
- the above S403 includes:
- control method further includes:
- calculating the first PWM signal according to the first reactive current reference value and the output current includes:
- the first PWM signal is calculated according to the limited first reactive current reference value and the output current.
- the grid-connected converter since the grid-connected converter needs to provide reactive power support to the grid during the fault ride-through process, it stops injecting active power into the grid, and cannot be disconnected from the grid within the preset ride-through time.
- reactive power is injected into the grid according to the voltage drop at the grid connection point, that is, reactive current needs to be injected into the grid to support the output voltage. Since the output reactive current may increase sharply with the change of the grid voltage, in order to ensure the safety of the grid-connected converter, this embodiment can limit the reactive power reference current.
- the formula for calculating the reference value of reactive current is as follows:
- I qc represents the first reactive current reference value
- I q 0 represents the initial current reactive component
- K n represents the reactive power support coefficient
- U n represents the rated voltage
- U represents the three-phase average voltage RMS
- I nmax represents the preset current value
- the voltage drop depth is ; I nmax is 1.1 times the rated current.
- the preset reference value is 1, as shown in FIG. 4 .
- FIG. 4 shows a calculation block diagram of the first active current reference value during the low voltage ride-through process.
- First take the positive sequence active component of the output voltage Divide by the rated voltage to get the positive sequence active power ratio, then, use the negative sequence active power component Divide by the rated voltage to obtain the negative sequence active power ratio, then subtract the positive sequence active power ratio from the preset reference value to obtain the first control variable, and add the first control variable and the negative sequence active power ratio to obtain the voltage dip depth. Then, multiply the voltage drop depth by the reactive power support coefficient K n to obtain the second control amount, and multiply the second control amount by the rated current to obtain the first reactive current value.
- the first reactive current value is Adding the initial current reactive component, the first reactive current reference value I qc is obtained.
- the reactive component of the initial current is the reactive component of the output current of the grid-connected converter at the moment before the low-voltage ride-through mode is entered.
- the first reactive current reference value I qc is the reactive current reference value in the low voltage ride-through mode.
- the first active current reference value I dc is a preset value.
- the first active current reference value I dc may be set to zero.
- the three-phase reactive current reference value in the voltage ride-through mode avoids the problem of low low-voltage ride-through capability caused by unified control of three-phase power, thereby ensuring the stable ride-through of the grid-connected converter under abnormal grid voltage conditions.
- S105 in FIG. 1 includes:
- S601 Extract the active component of the output current as the active component of the output current, and extract the reactive component of the output current as the reactive component of the output current;
- S604 Calculate the first PWM signal according to the first reactive current deviation value and the first active current deviation value.
- the first reactive current deviation value and the first active current deviation value are respectively input into the first PI controller to obtain the initial control amount in the low voltage ride-through mode, and then, The initial control amount in the low voltage ride through mode is converted from the dq coordinate system to the abc coordinate system to obtain the first target control amount, and finally, the first PWM signal is generated according to the first target control amount.
- the preset voltage value is used as the demarcation value of mode switching. If the output voltage is less than the preset voltage value, the switch K q is connected to K qc , the switch K d is connected to K dc , Thereby, the controller executes the control process of the low voltage ride-through mode. If the output voltage is greater than or equal to the preset voltage value, the switch K q is connected to K qr , and the switch K d is connected to K dr , so that the controller executes the normal operation mode. Control flow. If the output voltage does not recover to above the preset voltage value within the specified ride-through duration, the grid-connected converter is controlled to be disconnected from the grid. If the output voltage recovers to above the preset voltage value within the specified ride-through duration, the grid-connected converter is controlled to work in the normal working mode.
- FIG. 5 shows the structure of a control device 100 of a grid-connected converter.
- the control device 100 of a grid-connected converter includes:
- an acquisition module 110 configured to acquire the output voltage, output current and rated voltage of the grid-connected converter
- a low-voltage ride-through judging module 120 configured to judge that if the output voltage is less than a preset voltage value, then control the grid-connected converter to execute the low-voltage ride-through mode;
- an active component extraction module 130 configured to calculate the positive-sequence active component and the negative-sequence active component of the output voltage in the low-voltage ride-through mode
- the drop depth calculation module 140 is used to calculate the voltage drop depth according to the positive-sequence active component, the negative-sequence active component and the rated voltage of the output voltage;
- a first reactive current reference value calculation module 150 configured to calculate the first reactive current reference value according to the voltage drop depth
- the first PWM signal generation module 160 is configured to calculate the first PWM signal according to the first reactive current reference value and the output current, and the first PWM signal is used to control the grid-connected converter in the low voltage ride-through mode.
- control device 100 of the grid-connected converter further includes:
- the normal working mode judgment module is used to judge that if the output voltage is greater than or equal to the preset voltage value, then control the grid-connected converter to execute the normal working mode;
- the second PWM signal generating module is used to calculate the second PWM signal according to the output current and the given current value in the normal working mode, and the second PWM signal is used to control the grid-connected converter in the normal working mode.
- the drop depth calculation module 140 includes:
- the first ratio calculation unit is used to divide the positive sequence active power component of the output voltage by the rated voltage to obtain the positive sequence active power ratio;
- the second ratio calculation unit is used to divide the negative sequence active power component of the output voltage by the rated voltage to obtain the negative sequence active power ratio
- a first control quantity calculation unit used for subtracting the positive sequence active power ratio from the preset reference value to obtain the first control quantity
- the voltage dip depth calculation unit is used for adding the first control variable and the negative sequence active power ratio to obtain the voltage dip depth.
- the first reactive current reference value calculation module 150 includes:
- the rated current acquisition unit is used to acquire the rated current of the grid-connected converter
- the second control amount calculation unit is used to multiply the voltage drop depth by the reactive power support coefficient to obtain the second control amount
- the reactive current reference value calculation unit is configured to calculate the first reactive current reference value according to the second control amount and the rated current.
- the reactive current reference value calculation unit includes:
- a first reactive current calculation subunit used for multiplying the second control variable by the rated current to obtain the first reactive current value
- the initial current acquisition subunit is used to acquire the reactive power component of the initial current, and the reactive power component of the initial current is the reactive power component of the output current of the grid-connected converter before entering the low voltage ride-through mode;
- the first reactive current reference value calculation subunit is used for adding the first reactive current value and the initial current reactive component to obtain the first reactive current reference value.
- control device 100 of the grid-connected converter further includes:
- a limiter module used to limit the first reactive current reference value by using a preset current value
- the first PWM signal generating module 160 includes:
- the first PWM signal is calculated according to the limited first reactive current reference value and the output current.
- the first PWM signal generating module 160 specifically includes:
- a component extraction unit used for extracting the active component of the output current as the active component of the output current, and extracting the reactive component of the output current as the reactive component of the output current;
- a reactive current deviation value calculation unit configured to subtract the reactive component of the output current from the first reactive current reference value to obtain the first reactive current deviation value
- an active current deviation value calculation unit configured to subtract the active component of the output current from a preset first active current reference value to obtain a first active current deviation value
- the first PWM signal calculation unit is configured to calculate the first PWM signal according to the first reactive current deviation value and the first active current deviation value.
- each module included in the control device 100 of the grid-connected converter is used to implement the same functions as the steps in the above-mentioned various method embodiments.
- FIG. 6 is a schematic diagram of a grid-connected converter provided by an embodiment of the present application.
- the grid-connected converter 6 of this embodiment includes: a processor 60 , a memory 61 , and a computer program 62 stored in the memory 61 and executable on the processor 60 .
- the processor 60 executes the computer program 62
- the steps in each of the foregoing method embodiments are implemented, for example, steps 101 to 106 shown in FIG. 1 .
- the processor 60 executes the computer program 62
- the functions of the modules/units in the above-mentioned apparatus embodiments, for example, the functions of the modules 110 to 160 shown in FIG. 5 are implemented.
- the computer program 62 may be divided into one or more modules/units, which are stored in the memory 61 and executed by the processor 60 to complete the present application.
- One or more modules/units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 62 in the grid-connected converter 6 .
- the grid-connected converter 6 may be a computing device such as a desktop computer, a notebook computer, a handheld computer, and a cloud server.
- the grid-connected converter 6 may include, but is not limited to, a processor 60 and a memory 61 .
- grid-connected converter 6 is only an example of the grid-connected converter 6, and does not constitute a limitation on the grid-connected converter 6, and may include more or less components than those shown in the figure, or combine some Components, or different components, such as the grid-connected converter 6, may also include input and output devices, network access devices, buses, and the like.
- the processor 60 may be a central processing unit (Central Processing Unit, CPU), other general-purpose processors, digital signal processors (Digital Signal Processors, DSPs), application specific integrated circuits (Application Specific Integrated Circuits, ASICs), off-the-shelf programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
- CPU Central Processing Unit
- DSPs Digital Signal Processors
- ASICs Application Specific Integrated Circuits
- ASICs Application Specific Integrated Circuits
- FPGA Field-Programmable Gate Array
- a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
- the memory 61 may be an internal storage unit of the grid-connected converter 6 , such as a hard disk or a memory of the grid-connected converter 6 .
- the memory 61 can also be an external storage device of the grid-connected converter 6 , such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) equipped on the grid-connected converter 6 card, Flash Card, etc.
- the memory 61 may also include both an internal storage unit of the grid-connected converter 6 and an external storage device.
- the memory 61 is used to store computer programs and other programs and data required by the grid-connected converter.
- the memory 61 can also be used to temporarily store data that has been output or is to be output.
- the disclosed apparatus/grid-connected converter and method may be implemented in other ways.
- the above-described embodiments of the device/grid-connected converter are only illustrative.
- the division of modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple divisions. Units or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented.
- the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.
- Units described as separate components may or may not be physically separated, and components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
- each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
- the above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.
- the integrated modules/units if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer-readable storage medium.
- the present application realizes all or part of the processes in the methods of the above embodiments, and can also be completed by instructing relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program is in When executed by the processor, the steps of each of the above method embodiments can be implemented.
- the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate forms, and the like.
- Computer-readable media may include: any entity or device capable of carrying computer program code, recording media, USB flash drives, removable hard disks, magnetic disks, optical discs, computer memory, read-only memory (ROM, Read-Only Memory), random access Memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable media may be appropriately increased or decreased as required by the legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to the legislation and patent practice, the computer-readable media does not include Electrical carrier signals and telecommunication signals.
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Abstract
本申请适用于电路控制技术领域，提供了一种并网变流器的控制方法、装置及并网变流器，控制方法包括：判断输出电压大小，若输出电压小于预设电压值，则控制并网变流器执行低电压穿越模式；并在低电压穿越模式下，计算输出电压的正序有功分量和负序有功分量；根据输出电压的正序有功分量、负序有功分量和额定电压，计算电压跌落深度；最后根据电压跌落深度计算第一无功电流参考值；根据第一无功电流参考值和输出电流计算第一PWM信号。本申请在低压穿越控制中通过输出电压的正序分量和负序分量计算电压跌落深度，能够提高并网变流器的低电压穿越能力，保证并网变流器在输出电压异常情况下稳定穿越。
Description
本专利申请要求于2021年4月27日提交的中国专利申请No.CN202110461962.7的优先权。在先申请的公开内容通过整体引用并入本申请。
本申请属于电路控制技术领域，尤其涉及一种并网变流器的控制方法、装置及并网变流器。
光伏变流器是光伏发电系统中的关键部件，是将一种电能形式转换为另一种电能形式的电力变换器。在电网故障引起并网点电压涨跌时，分布式电源的并网变流器电网侧出口电流会升高，过高的电流可能会触发变流器过流保护机制动作而脱离电网。并网变流器随意离网容易导致电网波动，严重时甚至引起电力系统发生振荡，给电网带来损害。
目前，光伏并网变流器应对电网电压异常波动的运行控制策略主要是通过建立含有LCL滤波器的并网变流器数学模型计算出精确的电流指令，但是采用该方法控制的并网变流器的低电压穿越能力仍然较低，难以保证并网变流器在电网电压异常情况下稳定穿越。
有鉴于此，本申请实施例提供了一种并网变流器的控制方法、装置及并网变流器，以解决现有技术中并网变流器的低电压穿越能力较低的问题。
本申请采用的技术方案是：本申请实施例的第一方面提供了一种并网变流器的控制方法，包括：
获取步骤：获取并网变流器的输出电压、输出电流和额定电压；
低电压穿越判断步骤：若所述输出电压小于预设电压值，则控制所述并网变流器执行低电压穿越模式；
有功分量提取步骤：在所述低电压穿越模式下，计算所述输出电压的正序有功分量和负序有功分量；
跌落深度计算步骤：根据所述输出电压的正序有功分量、负序有功分量和所述额定电压，计算电压跌落深度；
第一无功电流参考值计算步骤：根据所述电压跌落深度计算第一无功电流参考值；
第一PWM信号生成步骤：根据所述第一无功电流参考值和所述输出电流计算第一PWM信号，所述第一PWM信号用于在所述低电压穿越模式下控制所述并网变流器。
本申请实施例的第二方面提供了一种并网变流器的控制装置，包括：
获取模块，用于获取并网变流器的输出电压、输出电流和额定电压；
低电压穿越判断模块，用于判断若所述输出电压小于预设电压值，则控制所述并网变流器执行低电压穿越模式；
有功分量提取模块，用于在所述低电压穿越模式下，计算所述输出电压的正序有功分量和负序有功分量；
跌落深度计算模块，用于根据所述输出电压的正序有功分量、负序有功分量和所述额定电压，计算电压跌落深度；
第一无功电流参考值计算模块，用于根据所述电压跌落深度计算第一无功电流参考值；
第一PWM信号生成模块，用于根据所述第一无功电流参考值和所述输出电流计算第一PWM信号，所述第一PWM信号用于在所述低电压穿越模式下控制所述并网变流器。
本申请实施例的第三方面提供了一种并网变流器，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如上所述并网变流器的控制方法的步骤。
本申请实施例的第四方面提供了一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，所述计算机程序被处理器执行时实现如上所述并网变流器的控制方法的步骤。
本申请实施例与现有技术相比存在的有益效果是：本实施例提供的并网变流器的控制方法首先判断输出电压的大小，若输出电压小于预设电压值，则控制并网变流器执行低电压穿越模式；并在低电压穿越模式下，计算输出电压的正序有功分量和负序有功分量；根据输出电压的正序有功分量、负序有功分量和额定电压，计算电压跌落深度；最后根据电压跌落深度计算第一无功电流参考值；根据第一无功电流参考值和输出电流计算第一PWM信号。本实施例在低压穿越控制中通过输出电压的正序分量和负序分量计算电压跌落深度，能够提高并网变流器的低电压穿越能力，保证并网变流器在输出电压异常情况下稳定穿越。
为了更清楚地说明本申请实施例中的技术方案，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申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1是本申请一实施例提供的并网变流器的控制方法的流程示意图；
图2是本申请一实施例提供的并网变流器的电路示意图；
图3是本申请一实施例提供的并网变流器的控制框图；
图4是本申请一实施例提供的第一无功电流参考值的计算框图；
图5是本申请一实施例提供的并网变流器的控制装置的结构示意图；
图6是本申请一实施例提供的并网变流器的示意图。
本申请的实施方式
以下描述中，为了说明而不是为了限定，提出了诸如特定系统结构、技术之类的具体细节，以便透彻理解本申请实施例。然而，本领域的技术人员应当清楚，在没有这些具体细节的其它实施例中也可以实现本申请。在其它情况中，省略对众所周知的系统、装置、电路以及方法的详细说明，以免不必要的细节妨碍本申请的描述。
为使本申请的目的、技术方案和优点更加清楚，下面将结合附图通过具体实施例来进行说明。
在一个实施例中，如图1所示，图1示出了本实施例提供的并网变流器的控制方法的实现流程，并网变流器的控制方法包括：
S101：获取并网变流器的输出电压、输出电流和额定电压。
在本实施例中，如图2所示，图2示出了并网变流器的电路图，其中并网变流器的输出电压为三相输出电压
u
ga
、
u
gb
和
u
gc
，输出电流为三相输出电流
i
ga
、
i
gb
和
i
gc
。本实施例的执行主体为与并网变流器连接，并用于控制并网变流器的控制器。
S102：若输出电压小于预设电压值，则控制并网变流器执行低电压穿越模式。
在本实施例中，预设电压值为额定电压的0.9倍。当输出电压小于预设电压值时，并网变流器进入低电压穿越模式，当输出电压大于或等于预设电压值时，并网变流器工作在正常工作模式。
S103：在低电压穿越模式下，计算输出电压的正序有功分量和负序有功分量。
在本实施例中，首先对三相输出电压
u
ga
、
u
gb
和
u
gc
进行Clark变换，得到
u
a
和
u
b
，然后对
u
a
和
u
b
进行Park变换，得到输出电压的正序有功分量
和负序有功分量
。
S104：根据输出电压的正序有功分量、负序有功分量和额定电压，计算电压跌落深度；
S105：根据电压跌落深度计算第一无功电流参考值；
S106：根据第一无功电流参考值和输出电流计算第一PWM信号，第一PWM信号用于在低电压穿越模式下控制并网变流器。
其中，PWM信号指的是脉冲宽度调制信号（PWM，英文全称为Pulse width
modulation）。
在本实施例中，对低电压穿越能力的评判标准主要包括：并网变流器的穿越持续时间和提供无功支撑功率的能力。例如，德国电气技术委员会于2018年发布的中高压并网认证标准VDE4110就是对穿越持续时间和提供无功支撑功率进行了规定。
为了提高低电压穿越能力，使并网变流器在低电压穿越过程中的穿越持续时间和无功支撑功率的提供能够满足标准要求，本实施例提供了一种并网变流器的控制方法，具体过程如下：
在abc坐标系中，当电网电压跌落发生时，电网侧输出电压、输出电流可以被写成：
式（1）~（2）中，
U
p 表示输出电压的正序电压幅值，
U
n 表示输出电压的负序电压幅值，
θ
p
表示正序电压相位角，
θ
n
表示负序电压相位角。
I
p
表示输出电流的正序电流幅值，
I
n 表示输出电流的负序电流幅值，
θ
1表示正序电流相对正序电压的相位角，
θ
2表示负序电流相对负序电压的相位角。
然后，
经过Clark、Park变换从abc坐标系中转换到同步旋转坐标系dq中：
考虑不对称电压跌落情况，并网变流器向电网输送的功率为：
整理后可以得出有功功率和无功功率的表达式为：
式（6）中，输出电流中的4个正负序分量
、
、
、
作为并网变流器的输出电流参考值需要求解，显然，只需要找出4个线性无关方程就可对输出电流中的4个正负序分量求解。不考虑无功功率的交流分量，同时忽略有功功率的交流分量（
P
c
=
P
s
=0），从式（6）中可以获得：
式（7）给出了通过给定的有功功率、无功功率和输出电压求出输出电流给定值的方法。为了确定低电压穿越过程中电压跌落深度与输出电流参考值的关系，本实施例通过电压跌落深度对电网电压跌落程度进行描述，同时，在跌落过程，有功功率
P
0和无功功率
Q
0难以准确描述，因此根据式（7），输出电流被进一步描述为：
其中：
考虑到在电压跌落前，电网中只有正序有功电压，因此在电压跌落前，可以认为式（9）中
k
d
、
k
q
表达式的后3项为0。同时假定式（8）中
P
0=
Q
0=
U
n
×
I
n
，式（9）中
，并将此假定带入式（8），可以得到输出电流参考值的最大值表达式为：
在实际情况中，用式（8）计算出来的输出电流参考值与式（10）计算值之间有一个确定的比例系数。定义比例系数
K
p
、
K
n
，并用比例系数改造式（10），可以得出：
上述式（11）给出了电网侧的输出电流参考值与电压跌落深度之间的线性关系，并且从式（11）可以看出，本实施例在计算输出电流参考值时，不仅采用电压跌落深度，还同时考虑输出电压的正序分量和负序分量，从而避免三相跌落不平衡时对各相进行统一控制造成的低电压穿越能力较差的问题。
从上述实施例可知，本实施例提供的并网变流器的控制方法首先判断输出电压的大小，若输出电压小于预设电压值，则控制并网变流器执行低电压穿越模式；并在低电压穿越模式下，计算输出电压的正序有功分量和负序有功分量；根据输出电压的正序有功分量、负序有功分量和额定电压，计算电压跌落深度；最后根据电压跌落深度计算第一无功电流参考值；根据第一无功电流参考值和输出电流计算第一PWM信号。本实施例通过在低压穿越控制中同时考虑输出电压的正向分量和负序分量计算输出电流参考值，能够提高并网变流器的低电压穿越能力，保证并网变流器在输出电压异常情况下稳定穿越。
在一个实施例中，在图1中S101之后，本实施例提供的控制方法还包括：
S201：若输出电压大于或等于预设电压值，则控制并网变流器执行正常工作模式；
S202：在正常工作模式下，根据输出电流和电流给定值计算第二PWM信号，第二PWM信号用于在正常工作模式下控制并网变流器。
在本实施例中，如图3所示，图3示出了本实施例提供的并网变流器的控制框图，具体地，在正常工作模式下，首先，将输出电流和电流给定值均从abc坐标系转换为dq坐标系下，然后，计算输出电流的有功分量
I
d
和无功分量
I
q
，计算电流给定值的有功分量
I
dr
和无功分量
I
qr
。将电流给定值的有功分量
I
dr
减去输出电流的有功分量
I
d
，得到正常工作模式下的有功电流偏差值，将电流给定值的有功分量
I
qr
减去输出电流的有功分量
I
q
，得到正常工作模式下的无功电流偏差值；接着分别将正常工作模式下的无功电流偏差值和有功电流偏差值输入第一PI控制器，得到正常工作模式下的初始控制量，然后将正常工作模式下的初始控制量由dq坐标系转换为abc坐标系，得到第二目标控制量，最后根据第二目标控制量生成第二PWM信号。
在一个实施例中，图1中的S104包括：
S301：将输出电压的正序有功分量除以额定电压，得到正序有功比值；
S302：将输出电压的负序有功分量除以额定电压，得到负序有功比值；
S303：采用预设基准值减去正序有功比值，得到第一控制量；
S304：将第一控制量与负序有功比值相加，得到电压跌落深度。
在一个实施例中，图1中的S105包括：
S401：获取并网变流器的额定电流；
S402：将电压跌落深度乘以无功支撑系数，得到第二控制量；
S403：根据第二控制量和额定电流计算第一无功电流参考值。
在一个实施例中，上述S403包括：
S501：将第二控制量与额定电流相乘，得到第一无功电流值；
S502：获取初始电流无功分量，初始电流无功分量为并网变流器在未进入低电压穿越模式前的输出电流的无功分量；
S503：将第一无功电流值与初始电流无功分量相加，得到第一无功电流参考值。
在一个实施例中，在S105之后，控制方法还包括：
采用预设电流值对第一无功电流参考值进行限幅；
相应地，根据第一无功电流参考值和输出电流计算第一PWM信号，包括：
根据限幅后的第一无功电流参考值和输出电流，计算第一PWM信号。
在本实施例中，由于在故障穿越过程中，并网变流器需向电网提供无功功率的支持，停止向电网注入有功功率，并且在预设穿越时间内不能离网。
式（12）中，
I
qc
表示第一无功电流参考值，
I
q
0表示初始电流无功分量，
K
n
表示无功支撑系数，
U
n
表示额定电压，
U表示三相平均电压有效值，
I
nmax
表示预设电流值；式（12）中，电压跌落深度为
；
I
nmax
为额定电流的1.1倍。
具体地，预设基准值为1，如图4所示，图4示出了低电压穿越过程中第一有功电流参考值的计算框图。首先，采用输出电压的正序有功分量
除以额定电压，得到正序有功比值，然后，采用负序有功分量
除以额定电压，得到负序有功比值，接着采用预设基准值减去正序有功比值，得到第一控制量，将第一控制量与负序有功比值相加，得到电压跌落深度。然后，将电压跌落深度与无功支撑系数
K
n
相乘，得到第二控制量，采用第二控制量与额定电流相乘，得到第一无功电流值，最后，将第一无功电流值加上初始电流无功分量，得到第一无功电流参考值
I
qc
。其中，初始电流无功分量为并网变流器在未进入低电压穿越模式前一时刻的输出电流的无功分量。
在本实施例中，第一无功电流参考值
I
qc
为低电压穿越模式下的无功电流参考值。第一有功电流参考值
I
dc
为预设值。
具体地，由于在故障穿越过程中并网变流器停止向电网注入有功功率，因此，第一有功电流参考值
I
dc
可以设置为零。
从上述实施例可知，本实施例在计算电压跌落深度时，不仅考虑输出电压的正序有功分量，还同时考虑负序有功分量，从而能够在三相电压不平衡时考虑三相跌落情况计算低电压穿越模式下三相的无功电流参考值，避免对三相电进行统一控制造成的低电压穿越能力低的问题，进而保证并网变流器在电网电压异常情况下的稳定穿越。
在一个实施例中，图1中的S105包括：
S601：提取输出电流的有功分量作为输出电流有功分量，并提取输出电流的无功分量作为输出电流无功分量；
S602：采用第一无功电流参考值减去输出电流无功分量，得到第一无功电流偏差值；
S603：采用预设的第一有功电流参考值减去输出电流有功分量，得到第一有功电流偏差值；
S604：根据第一无功电流偏差值和第一有功电流偏差值，计算第一PWM信号。
在本实施例中，如图3所示，首先，分别将第一无功电流偏差值和第一有功电流偏差值输入第一PI控制器，得到低电压穿越模式下的初始控制量，然后，将低电压穿越模式下的初始控制量由dq坐标系转换为abc坐标系，得到第一目标控制量，最后，根据第一目标控制量生成第一PWM信号。
在本实施例中，如图3所示，以预设电压值作为模式切换的分界值，若输出电压小于预设电压值，则开关
K
q
与
K
qc
连接，开关
K
d
与
K
dc
连接，从而使控制器执行低电压穿越模式的控制流程，若输出电压大于或等于预设电压值，则开关
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连接，开关
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连接，从而使控制器执行正常工作模式的控制流程。若在规定的穿越持续时间内输出电压未恢复到预设电压值以上，则控制并网变流器脱网。若在规定的穿越持续时间内输出电压恢复到预设电压值以上，则控制并网变流器工作在正常工作模式。
应理解，上述实施例中各步骤的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
在一个实施例中，如图5所示，图5示出了一种并网变流器的控制装置100的结构，并网变流器的控制装置100包括：
获取模块110，用于获取并网变流器的输出电压、输出电流和额定电压；
低电压穿越判断模块120，用于判断若输出电压小于预设电压值，则控制并网变流器执行低电压穿越模式；
有功分量提取模块130，用于在低电压穿越模式下，计算输出电压的正序有功分量和负序有功分量；
跌落深度计算模块140，用于根据输出电压的正序有功分量、负序有功分量和额定电压，计算电压跌落深度；
第一无功电流参考值计算模块150，用于根据电压跌落深度计算第一无功电流参考值；
第一PWM信号生成模块160，用于根据第一无功电流参考值和输出电流计算第一PWM信号，第一PWM信号用于在低电压穿越模式下控制并网变流器。
在一个实施例中，并网变流器的控制装置100还包括：
正常工作模式判断模块，用于判断若输出电压大于或等于预设电压值，则控制并网变流器执行正常工作模式；
第二PWM信号生成模块，用于在正常工作模式下，根据输出电流和电流给定值计算第二PWM信号，第二PWM信号用于在正常工作模式下控制并网变流器。
在一个实施例中，跌落深度计算模块140包括：
第一比值计算单元，用于将输出电压的正序有功分量除以额定电压，得到正序有功比值；
第二比值计算单元，用于将输出电压的负序有功分量除以额定电压，得到负序有功比值；
第一控制量计算单元，用于采用预设基准值减去正序有功比值，得到第一控制量；
电压跌落深度计算单元，用于将第一控制量与负序有功比值相加，得到电压跌落深度。
在一个实施例中，第一无功电流参考值计算模块150包括：
额定电流获取单元，用于获取并网变流器的额定电流；
第二控制量计算单元，用于将电压跌落深度乘以无功支撑系数，得到第二控制量；
无功电流参考值计算单元，用于根据第二控制量和额定电流计算第一无功电流参考值。
在一个实施例中，无功电流参考值计算单元包括：
第一无功电流计算子单元，用于将第二控制量与额定电流相乘，得到第一无功电流值；
初始电流获取子单元，用于获取初始电流无功分量，初始电流无功分量为并网变流器在未进入低电压穿越模式前的输出电流的无功分量；
第一无功电流参考值计算子单元，用于将第一无功电流值与初始电流无功分量相加，得到第一无功电流参考值。
在一个实施例中，并网变流器的控制装置100还包括：
限幅模块，用于采用预设电流值对第一无功电流参考值进行限幅；
相应地，第一PWM信号生成模块160包括：
根据限幅后的第一无功电流参考值和输出电流，计算第一PWM信号。
在一个实施例中，第一PWM信号生成模块160具体包括：
分量提取单元，用于提取输出电流的有功分量作为输出电流有功分量，并提取输出电流的无功分量作为输出电流无功分量；
无功电流偏差值计算单元，用于采用第一无功电流参考值减去输出电流无功分量，得到第一无功电流偏差值；
有功电流偏差值计算单元，用于采用预设的第一有功电流参考值减去输出电流有功分量，得到第一有功电流偏差值；
第一PWM信号计算单元，用于根据第一无功电流偏差值和第一有功电流偏差值，计算第一PWM信号。
可以理解的是，并网变流器的控制装置100所包括的各个模块用于实现与上述各个方法实施例中的步骤相同的功能。
图6是本申请一实施例提供的并网变流器的示意图。如图6所示，该实施例的并网变流器6包括：处理器60、存储器61以及存储在存储器61中并可在处理器60上运行的计算机程序62。处理器60执行计算机程序62时实现上述各个方法实施例中的步骤，例如图1所示的步骤101至106。或者，处理器60执行计算机程序62时实现上述各装置实施例中各模块/单元的功能，例如图5所示模块110至160的功能。
计算机程序62可以被分割成一个或多个模块/单元，一个或者多个模块/单元被存储在存储器61中，并由处理器60执行，以完成本申请。一个或多个模块/单元可以是能够完成特定功能的一系列计算机程序指令段，该指令段用于描述计算机程序62在并网变流器6中的执行过程。并网变流器6可以是桌上型计算机、笔记本、掌上电脑及云端服务器等计算设备。并网变流器6可以包括，但不仅限于，处理器60、存储器61。本领域技术人员可以理解，图6仅仅是并网变流器6的示例，并不构成对并网变流器6的限定，可以包括比图示更多或更少的部件，或者组合某些部件，或者不同的部件，例如并网变流器6还可以包括输入输出设备、网络接入设备、总线等。
处理器60可以是中央处理单元(Central
Processing Unit，CPU)，还可以是其他通用处理器、数字信号处理器 (Digital Signal Processor，DSP)、专用集成电路 (Application Specific Integrated Circuit，ASIC)、现成可编程门阵列
(Field-Programmable Gate Array，FPGA) 或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
存储器61可以是并网变流器6的内部存储单元，例如并网变流器6的硬盘或内存。存储器61也可以是并网变流器6的外部存储设备，例如并网变流器6上配备的插接式硬盘，智能存储卡（Smart Media Card，SMC），安全数字（Secure Digital，SD）卡，闪存卡（Flash Card）等。此外，存储器61还可以既包括并网变流器6的内部存储单元也包括外部存储设备。存储器61用于存储计算机程序以及并网变流器所需的其他程序和数据。存储器61还可以用于暂时地存储已经输出或者将要输出的数据。
所属领域的技术人员可以清楚地了解到，为了描述的方便和简洁，仅以上述各功能单元、模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能单元、模块完成，即将装置的内部结构划分成不同的功能单元或模块，以完成以上描述的全部或者部分功能。实施例中的各功能单元、模块可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中，上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。另外，各功能单元、模块的具体名称也只是为了便于相互区分，并不用于限制本申请的保护范围。上述系统中单元、模块的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详述或记载的部分，可以参见其它实施例的相关描述。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
在本申请所提供的实施例中，应该理解到，所揭露的装置/并网变流器和方法，可以通过其它的方式实现。例如，以上所描述的装置/并网变流器实施例仅仅是示意性的，例如，模块或单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通讯连接可以是通过一些接口，装置或单元的间接耦合或通讯连接，可以是电性，机械或其它的形式。
作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
集成的模块/单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请实现上述实施例方法中的全部或部分流程，也可以通过计算机程序来指令相关的硬件来完成，的计算机程序可存储于一计算机可读存储介质中，该计算机程序在被处理器执行时，可实现上述各个方法实施例的步骤。。其中，计算机程序包括计算机程序代码，计算机程序代码可以为源代码形式、对象代码形式、可执行文件或某些中间形式等。计算机可读介质可以包括：能够携带计算机程序代码的任何实体或装置、记录介质、U盘、移动硬盘、磁碟、光盘、计算机存储器、只读存储器（ROM，Read-Only Memory）、随机存取存储器（RAM，Random Access Memory）、电载波信号、电信信号以及软件分发介质等。需要说明的是，计算机可读介质包含的内容可以根据司法管辖区内立法和专利实践的要求进行适当的增减，例如在某些司法管辖区，根据立法和专利实践，计算机可读介质不包括电载波信号和电信信号。
以上所述实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围，均应包含在本申请的保护范围之内。
Claims (10)
- 一种并网变流器的控制方法，其特征在于，包括：获取步骤：获取并网变流器的输出电压、输出电流和额定电压；低电压穿越判断步骤：若所述输出电压小于预设电压值，则控制所述并网变流器执行低电压穿越模式；有功分量提取步骤：在所述低电压穿越模式下，计算所述输出电压的正序有功分量和负序有功分量；跌落深度计算步骤：根据所述输出电压的正序有功分量、负序有功分量和所述额定电压，计算电压跌落深度；第一无功电流参考值计算步骤：根据所述电压跌落深度计算第一无功电流参考值；第一PWM信号生成步骤：根据所述第一无功电流参考值和所述输出电流计算第一PWM信号，所述第一PWM信号用于在所述低电压穿越模式下控制所述并网变流器。
- 如权利要求1所述的并网变流器的控制方法，其特征在于，在所述获取步骤之后，所述控制方法还包括：若所述输出电压大于或等于所述预设电压值，则控制所述并网变流器执行正常工作模式；在所述正常工作模式下，根据所述输出电流和电流给定值计算第二PWM信号，所述第二PWM信号用于在所述正常工作模式下控制所述并网变流器。
- 如权利要求1所述的并网变流器的控制方法，其特征在于，所述跌落深度计算步骤，包括：将所述输出电压的正序有功分量除以所述额定电压，得到正序有功比值；将所述输出电压的负序有功分量除以所述额定电压，得到负序有功比值；采用预设基准值减去所述正序有功比值，得到第一控制量；将所述第一控制量与所述负序有功比值相加，得到所述电压跌落深度。
- 如权利要求1所述的并网变流器的控制方法，其特征在于，所述第一无功电流参考值计算步骤，包括：获取所述并网变流器的额定电流；将所述电压跌落深度乘以无功支撑系数，得到第二控制量；根据所述第二控制量和所述额定电流计算所述第一无功电流参考值。
- 如权利要求4所述的并网变流器的控制方法，其特征在于，所述根据所述第二控制量和所述额定电流计算所述第一无功电流参考值，包括：将所述第二控制量与所述额定电流相乘，得到第一无功电流值；获取初始电流无功分量，所述初始电流无功分量为所述并网变流器在未进入所述低电压穿越模式前的输出电流的无功分量；将所述第一无功电流值与所述初始电流无功分量相加，得到所述第一无功电流参考值。
- 如权利要求5所述的并网变流器的控制方法，其特征在于，在所述将所述第一无功电流值与所述初始电流无功分量相加，得到所述第一无功电流参考值之后，所述控制方法还包括：采用预设电流值对所述第一无功电流参考值进行限幅；相应地，所述第一PWM信号生成步骤，包括：根据限幅后的第一无功电流参考值和所述输出电流，计算所述第一PWM信号。
- 如权利要求1至6任一项所述的并网变流器的控制方法，其特征在于，所述第一PWM信号生成步骤，包括：提取所述输出电流的有功分量作为输出电流有功分量，并提取所述输出电流的无功分量作为输出电流无功分量；采用所述第一无功电流参考值减去所述输出电流无功分量，得到第一无功电流偏差值；采用预设的第一有功电流参考值减去所述输出电流有功分量，得到第一有功电流偏差值；根据所述第一无功电流偏差值和所述第一有功电流偏差值，计算所述第一PWM信号。
- 一种并网变流器的控制装置，其特征在于，包括：获取模块，用于获取并网变流器的输出电压、输出电流和额定电压；低电压穿越判断模块，用于判断若所述输出电压小于预设电压值，则控制所述并网变流器执行低电压穿越模式；有功分量提取模块，用于在所述低电压穿越模式下，计算所述输出电压的正序有功分量和负序有功分量；跌落深度计算模块，用于根据所述输出电压的正序有功分量、负序有功分量和所述额定电压，计算电压跌落深度；第一无功电流参考值计算模块，用于根据所述电压跌落深度计算第一无功电流参考值；第一PWM信号生成模块，用于根据所述第一无功电流参考值和所述输出电流计算第一PWM信号，所述第一PWM信号用于在所述低电压穿越模式下控制所述并网变流器。
- 一种并网变流器，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，其特征在于，所述处理器执行所述计算机程序时实现如权利要求1至7任一项所述控制方法的步骤。
- 一种计算机可读存储介质，所述计算机可读存储介质存储有计算机程序，其特征在于，所述计算机程序被处理器执行时实现如权利要求1至7任一项所述控制方法的步骤。
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