WO2021179710A1 - 一种模块化多电平变换器直流电容选取方法及装置 - Google Patents

一种模块化多电平变换器直流电容选取方法及装置 Download PDF

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WO2021179710A1
WO2021179710A1 PCT/CN2020/134887 CN2020134887W WO2021179710A1 WO 2021179710 A1 WO2021179710 A1 WO 2021179710A1 CN 2020134887 W CN2020134887 W CN 2020134887W WO 2021179710 A1 WO2021179710 A1 WO 2021179710A1
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voltage
capacitance
bridge
sub
maximum allowable
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PCT/CN2020/134887
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French (fr)
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唐德平
蔡振鸿
关磊
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合肥科威尔电源系统股份有限公司
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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

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  • the invention relates to the field of power electronics, and more particularly to a method and device for selecting a DC capacitor of a modular multilevel converter.
  • High Voltage Direct Current Transmission has the economic advantages of low operating power loss, narrow line corridors, low line cost, and technical advantages such as fast adjustment speed, reliable operation, stable output, and relatively stable voltage distribution. With these advantages, HVDC has become the preferred transmission method for long-distance, large-capacity power transmission.
  • VSC Voltage Source Converter
  • CSC Current Source Converter
  • Modular multilevel converter came into being. Because of its highly modular structure, it is easy to expand the system and realize redundant control. It has the advantages of low switching frequency and good output voltage waveform. Modular multilevel converter The structure has significantly smaller harmonic output, electromagnetic interference and switching loss. Its topology ensures that the balance control of the module capacitor voltage is simplified, the output waveform quality of the AC side is good, and there is no need to configure a filter device. At the same time, the components are simple in voltage equalization, the loss is significantly reduced, and the system cost is reduced. The redundant matching also makes the system fault handling capability stronger and more reliable. Has become the mainstay of current multilevel converter applications.
  • the sub-module capacitor is the most important energy storage component of the modular multi-level converter.
  • the choice of capacitor is very important for modular multilevel converters.
  • the document "New Modularized Multilevel Converter Capacitor Voltage Control" aims at the main circuit of the three-phase voltage type modularized multilevel converter, and elaborates the calculation of active power and reactive power and the control of AC and DC voltages. Finally, it is concluded that it is possible to use active and reactive power, AC and DC voltage to control each independent sub-module to achieve rectification control, but its entire technical solution lacks research on the energy storage components of modular multi-level converters. , Lack of a reasonable selection method for sub-module capacitors, so it is difficult to guarantee the power transmission on the AC and DC sides of the converter and the DC bus voltage support.
  • the technical problem to be solved by the present invention is how to provide a set of reasonable sub-module capacitor selection methods to better undertake the functions of power transmission on the AC and DC sides of the converter and DC bus voltage support.
  • the present invention solves the above technical problems through the following technical means: a method for selecting a DC capacitor of a modular multilevel converter, the method is applied to the main circuit of a three-phase voltage type modular multilevel converter, and the method include:
  • Step 1 Establish a constraint model for capacitance and maximum allowable volatility
  • Step 2 Establish a constraint model for the maximum allowable excess voltage and capacitance
  • Step 3 Establish a constraint model for the voltage capability requirements and capacitance of the sub-module
  • Step 4 Comprehensively compare the constraint model of the capacitance and the maximum allowable volatility, the constraint model of the maximum allowable excess voltage and capacitance, and the sub-module voltage capability requirement and the constraint model of the capacitance. Choose the constraints of the three models. The maximum value of the range is used as the final capacitor selection condition, and the capacitor selection is performed according to the capacitor selection condition.
  • the present invention establishes a universally applicable constraint model, can select capacitors according to different constraint requirements, and has more general applicability; from a modular multilevel controller
  • the work started with a good consideration of the constraints of its stable operation and safe operation.
  • Each model fully considered the safe operation and stable operation of the modular multilevel converter, and finally the maximum value of the constraint range of the three models was taken as the final
  • the capacitor selection conditions are safer and more reliable, and the power transmission on the AC and DC sides of the converter and the DC bus voltage support are guaranteed.
  • the main circuit of the three-phase voltage type modular multilevel converter includes three bridge arms, each bridge arm includes an upper half bridge and a lower half bridge, and both the upper half bridge and the lower half bridge are composed of N sub-modules. Connected in series, one end of all upper half bridges are connected together to form the positive voltage of the DC side, the other end of all upper half bridges are connected in series with an inductor, and one end of all lower half bridges are connected in series with another inductor.
  • the inductance of the upper half bridge of each bridge arm is connected in series with the inductance of the lower half bridge connected in series, the other ends of all the lower half bridges are connected together to form the negative pole of the DC side voltage, and the middle point of each bridge arm leads out a wire Connect the three-phase lines of the three-phase AC voltage source respectively.
  • the formula Establish a constraint model for capacitance and maximum allowable volatility, where ⁇ is the angular frequency; ⁇ is the maximum allowable volatility; n is the number of sub-modules in each bridge arm; I dc is the DC side current; U dc is the DC side voltage; U SMij is the voltage of the sub-module SMij; m is the modulation index and V s is the AC side voltage, and V dc is equivalent to U dc ; Represents the power factor angle of the modular multilevel converter.
  • I S represents the root mean square value of the alternating current
  • t represents the time
  • V ex is the maximum allowable excess voltage
  • V SMdc is the half-bridge voltage
  • V r is the maximum adjustable voltage
  • N is the total number of sub-modules on the half-bridge
  • max is the maximum value.
  • the present invention also provides a DC capacitor selection device for a modular multilevel converter, which is applied to the main circuit of a three-phase voltage type modular multilevel converter, and the device includes:
  • the first model building module is used to build a constraint model of capacitance and maximum allowable volatility
  • the second model establishment module is used to establish the constraint model of the maximum allowable excess voltage and capacitance
  • the third model establishment module is used to establish the constraint model of sub-module voltage capability requirements and capacitance
  • Capacitor selection module used to comprehensively compare the constraint model of the capacitance and the maximum allowable volatility, the constraint model of the maximum allowable withstand excess voltage and capacitance, and the constraint range of the sub-module voltage capability requirements and the constraint model of the capacitance. Choose three types The maximum value of the constraint range in the model is used as the final capacitor selection condition, and the capacitor selection is performed according to the capacitor selection condition.
  • the main circuit of the three-phase voltage type modular multilevel converter includes three bridge arms, each bridge arm includes an upper half bridge and a lower half bridge, and both the upper half bridge and the lower half bridge are composed of N sub-modules. Connected in series, one end of all upper half bridges are connected together to form the positive voltage of the DC side, the other end of all upper half bridges are connected in series with an inductor, and one end of all lower half bridges are connected in series with another inductor. , The inductance of the upper half bridge of each bridge arm is connected in series with the inductance of the lower half bridge. The other ends of all the lower half bridges are connected together to form the negative pole of the DC side voltage, and the middle point of each bridge arm leads out a wire Connect the three-phase lines of the three-phase AC voltage source respectively.
  • the first model establishment module is further used for: using formula Establish a constraint model for capacitance and maximum allowable volatility, where ⁇ is the angular frequency; ⁇ is the maximum allowable volatility; n is the number of sub-modules in each bridge arm; I dc is the DC side current; U dc is the DC side voltage; U SMij is the voltage of the sub-module SMij; m is the modulation index and V s is the AC side voltage, and V dc is equivalent to U dc ; Represents the power factor angle of the modular multilevel converter.
  • the second model establishment module is further used for: using formula
  • I S represents the root mean square value of the alternating current
  • t represents the time
  • V ex is the maximum allowable excess voltage
  • V SMdc is the half-bridge voltage
  • V r is the maximum adjustable voltage
  • N is the total number of sub-modules on the half-bridge
  • max is the maximum value.
  • the third model establishment module is further used for: using formulas
  • the advantage of the present invention is that: the present invention has established a universally applicable constraint model for the lack of a set of reasonable sub-module capacitor selection methods in the prior art, and can select capacitors according to different constraint requirements, and has universal applicability;
  • the work of the modular multilevel controller takes into account the constraints of its stable operation and safe operation. Each model fully considers the safe operation and stable operation of the modular multilevel converter, and finally uses the three models The maximum value of the constraint range is used as the final capacitor selection condition, which is safer and more reliable, and the power transmission on the AC and DC sides of the converter and the DC bus voltage support are guaranteed.
  • FIG. 1 is a flowchart of a method for selecting a DC capacitor of a modular multilevel converter disclosed in an embodiment of the present invention
  • FIG. 2 is a topological diagram of the main circuit of a three-phase voltage type modular multilevel converter in a method for selecting a DC capacitor of a modular multilevel converter disclosed in an embodiment of the present invention
  • FIG. 3 is a schematic diagram of sub-modules in the main circuit of a three-phase voltage type modular multilevel converter in a method for selecting a DC capacitor of a modular multilevel converter disclosed in an embodiment of the present invention.
  • a method for selecting DC capacitors of a modular multilevel converter is applied to the main circuit of a three-phase voltage type modular multilevel converter, and the main circuit is a circuit of the prior art.
  • Figure 2 it is a topological diagram of the main circuit of a three-phase voltage type modular multilevel converter in the prior art, and its structure is that the main circuit of the three-phase voltage type modular multilevel converter includes Three bridge arms, each of which includes an upper half bridge and a lower half bridge. Both the upper half bridge and the lower half bridge are composed of N sub-modules connected in series. The sub-module SMN forms a half bridge.
  • the upper half bridge is located in the upper half of the entire bridge arm, and the lower half bridge is located in the lower half of the entire bridge arm. All the other ends of the upper half bridges are connected in series with an inductor, and all the ends of the lower half bridges are connected with another inductance in series.
  • phase a in Figure 2 represents A Phase
  • phase b represents phase B
  • phase c represents phase C
  • ac side represents AC side
  • dc side represents DC side
  • V SMdc half-bridge voltage
  • V dc is equivalent to U dc is DC side voltage
  • V SMij is equivalent to U SMij Is the voltage of the sub-module SMij
  • i arm is the branch current, that is, the current of each bridge arm.
  • Figure 3 shows the schematic diagram of each sub-module.
  • Each sub-module is composed of two switching tubes and a capacitor.
  • the emitter of one switching tube is connected to the collector of another switching tube, and the collector of one switching tube is connected to the other.
  • a capacitor is connected between the emitters of the switching tubes, and the voltage of the sub-module is between the emitter of one switching tube and the collector of the other switching tube. Since the main circuit is a relatively common circuit in the prior art, its circuit principle and detailed structure are not described here.
  • the method includes:
  • Step S1 Establish a constraint model for capacitance and maximum allowable volatility; specifically: since each switch tube in the sub-module will bear the capacitor voltage separately, excessive capacitor voltage fluctuations not only affect the selection of the capacitor's own withstand voltage, but may also threaten The safe operation area of the switching device, so the maximum allowable fluctuation rate must be taken into consideration in the selection process of the capacitor.
  • the maximum allowable fluctuation rate of the normal operating capacitor voltage is generally given, and the formula is used according to the relationship between the energy change and the actual energy fluctuation
  • ⁇ is the angular frequency
  • ⁇ is the maximum allowable volatility
  • n is the number of sub-modules in each bridge arm
  • I dc is the DC side current
  • U dc is the DC side voltage
  • U SMij is the voltage of the sub-module SMij
  • m is the modulation index
  • V s is the AC side voltage
  • V dc is equivalent to U dc
  • This model limits the selection range of the capacitor when the capacitor voltage fluctuation is considered, and C Sel1 is the capacitance value when the capacitor voltage fluctuation is considered.
  • Step S2 Establish a constraint model of the maximum allowable excess voltage and capacitance; the specific process is: in a modular multilevel converter, the output voltage of each sub-module is equal to the voltage of the capacitor in the module, in order to ensure the normal operation of the converter During operation, the capacitor voltage must always be lower than the voltage limit of various devices in the sub-module, so there are V ex is the maximum allowable excess voltage, V SMdc is the half-bridge voltage, and V r represents the maximum adjustable voltage. Of course, the capacitor allows a certain amount of over-rated voltage, which is generally called the maximum allowable excess voltage. In practice, the maximum allowable excess voltage will be given. According to the principle that the maximum allowable excess voltage is greater than the actual voltage, use the formula Establish a constraint model for the maximum allowable excess voltage and capacitance;
  • I S represents the root mean square value of the alternating current
  • t represents the time
  • N represents the total number of sub-modules on the half-bridge
  • max represents the maximum value.
  • C Sel2 is the capacitance value when the maximum allowable withstand excess voltage is considered.
  • Step S3 Establish a constraint model for the voltage capability requirements and capacitance of the sub-module; the specific process is: in order to ensure that the voltage output of each bridge arm can be continuously stable, the voltage of the sub-module is limited, that is, the total The capacitor voltage of the sub-module must be sufficient to synthesize the required bridge arm voltage at any time to provide the required associated phase voltage, so use the formula
  • C Sel3 is the capacitance value that considers the voltage capability requirements of the sub-modules.
  • Step S4 Comprehensively compare the constraint model of the capacitance and the maximum allowable volatility rate, the constraint model of the maximum allowable withstand excess voltage and capacitance, and the constraint range of the sub-module voltage capability requirements and the constraint model of the capacitance, and select the constraints of the three models
  • the maximum value of the range is used as the final capacitor selection condition, and the capacitor selection is performed according to the capacitor selection conditions.
  • the selected capacitor can ensure the continuous and stable operation of the circuit, fully consider the safe operation of the modular multilevel converter, and establish universally applicable constraints. Models can be selected according to different constraint requirements, and they are more universally applicable.
  • the range of C Sel1 is greater than 6, the range of C Sel2 is greater than 4, and the range of C Sel3 is greater than 2, the maximum value of the constraint range in the three models is greater than 6, and the final capacitor selection condition is that the capacitance value is greater than 6. .
  • the method for selecting DC capacitors of modular multilevel converters is mainly aimed at the lack of a set of reasonable sub-module capacitor selection methods in the prior art, and establishes a universally applicable constraint model, which can target The selection of capacitors with different constraint requirements is more universally applicable; starting from the work of modular multilevel controllers, the constraints of stable operation and safe operation are well considered.
  • Each model fully considers the modular multi-electricity The safe operation and stable operation of the flat converter, and finally the maximum value of the constraint range in the three models is used as the final capacitor selection condition, which is safer and more reliable.
  • the AC and DC side power transmission of the converter and the DC bus voltage support are guaranteed.
  • Embodiment 2 of the present invention also provides a DC capacitor selection device for a modular multilevel converter, which is applied to the main circuit of a three-phase voltage type modular multilevel converter ,
  • the device includes:
  • the first model building module is used to build a constraint model of capacitance and maximum allowable volatility
  • the second model establishment module is used to establish the constraint model of the maximum allowable excess voltage and capacitance
  • the third model establishment module is used to establish the constraint model of sub-module voltage capability requirements and capacitance
  • Capacitor selection module used to comprehensively compare the constraint model of the capacitance and the maximum allowable volatility, the constraint model of the maximum allowable withstand excess voltage and capacitance, and the constraint range of the sub-module voltage capability requirements and the constraint model of the capacitance. Choose three types The maximum value of the constraint range in the model is used as the final capacitor selection condition, and the capacitor selection is performed according to the capacitor selection condition.
  • the main circuit of the three-phase voltage type modular multilevel converter includes three bridge arms, each bridge arm includes an upper half bridge and a lower half bridge, and both the upper half bridge and the lower half bridge are composed of N sub-modules. Connected in series, one end of all upper half bridges are connected together to form the positive voltage of the DC side, the other end of all upper half bridges are connected in series with an inductor, and one end of all lower half bridges are connected in series with another inductor. , The inductance of the upper half bridge of each bridge arm is connected in series with the inductance of the lower half bridge. The other ends of all the lower half bridges are connected together to form the negative pole of the DC side voltage, and the middle point of each bridge arm leads out a wire Connect the three-phase lines of the three-phase AC voltage source respectively.
  • the first model establishment module is also used to: use the formula Establish a constraint model for capacitance and maximum allowable volatility, where ⁇ is the angular frequency; ⁇ is the maximum allowable volatility; n is the number of sub-modules in each bridge arm; I dc is the DC side current; U dc is the DC side voltage; U SMij is the voltage of the sub-module SMij; m is the modulation index and V s is the AC side voltage, and V dc is equivalent to U dc ; Represents the power factor angle of the modular multilevel converter.
  • the second model establishment module is also used to: use the formula
  • I S represents the root mean square value of the alternating current
  • t represents the time
  • V ex is the maximum allowable excess voltage
  • V SMdc is the half-bridge voltage
  • V r is the maximum adjustable voltage
  • N is the total number of sub-modules on the half-bridge
  • max is the maximum value.
  • the third model establishment module is also used to: use the formula

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Abstract

一种模块化多电平变换器直流电容选取方法及装置，所述方法应用于三相电压型模块化多电平变换器的主电路，所述方法包括：建立电容与最大允许波动率的约束模型(S1)；建立最大允许承受超额电压与电容的约束模型(S2)；建立子模块电压能力要求与电容的约束模型(S3)；综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取(S4)；该方法能更好的承担换流器交直流侧功率传输、直流母线电压支撑的作用。

Description

一种模块化多电平变换器直流电容选取方法及装置 技术领域
本发明涉及电力电子领域，更具体涉及模块化多电平变换器直流电容选取方法及装置。
背景技术
近几十年，随着社会的发展，工业与生活中对远距离高功率输电的需求越来越多要求也越来越高，传统的交流输电的缺点也越来越明显，直流输电具有功率调节快速方便、稳定性强、安全性高、成本低等诸多优点，因此应用越来越广泛。随着全控型开关器件IGBT等的发展使直流输电技术进一步飞跃。而高压直流输电(High Voltage Direct Current Transmission,HVDC)具有运行功率损耗小、线路走廊狭窄、线路造价低的经济性优势以及调节速度快、运行可靠、输出稳定、电压分布相对平稳等的技术性优势，凭借这些优势，HVDC已成为远距离、大容量输电的首选输电方式。
在输电技术中变换器起着无法替代的作用，换流器的主要作用是交直变换。而电压源变换器(Voltage Source Converter，VSC)和电流源型变换器(Current Source Converter,CSC)的发展使HVDC输电的也随之得到快速发展。但是随着一些应用领域对电压功率要求越来越高，传统的VSC拓扑结构无法满足这些领域的要求。
模块化多电平变换器应运而生，由于其拓扑采用高度的模块化结构，易于扩展系统和实现冗余控制，具有开关频率低，输出电压波形良好等优点，模块化多电平换流器的结构有着明显更小的谐波输出、电磁干扰及开 关损耗。其拓扑保证了模块电容电压的均衡控制得到简化，交流侧输出波形质量好，无需配置滤波装置。同时器件均压简单，损耗显著降低，降低了系统成本，冗余匹配也让系统故障处理能力强从而更可靠。已经成为当前多电平变换器应用的支柱力量。
对模块化多电平变换器而言，子模块电容作为模块化多电平变换器最重要的储能元件，承担着换流器交直流侧功率传输、直流母线电压支撑的作用，因此子模块电容的选取对于模块化多电平变换器至关重要。文献《新型模块化多电平变换器电容电压控制》其针对三相电压型模块化多电平变换器的主电路，对有功功率和无功功率的计算以及交直流变电压控制进行了阐述，最后得出结论，采用有功和无功、交流和直流电压控制每个独立的子模块来实现整流控制是可能的，但是其整个技术方案缺乏对模块化多电平变换器的储能元件的研究，缺乏一套合理的子模块电容选取方法，因此换流器交直流侧功率传输、直流母线电压支撑难以得到保障。
发明内容
本发明所要解决的技术问题在于如何提供一套合理的子模块电容选取方法，更好的承担换流器交直流侧功率传输、直流母线电压支撑的作用。
本发明通过以下技术手段实现解决上述技术问题的：一种模块化多电平变换器直流电容选取方法，所述方法应用于三相电压型模块化多电平变换器的主电路，所述方法包括：
步骤一：建立电容与最大允许波动率的约束模型；
步骤二：建立最大允许承受超额电压与电容的约束模型；
步骤三：建立子模块电压能力要求与电容的约束模型；
步骤四：综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取。
本发明针对现有技术缺乏一套合理的子模块电容选取方法，建立了普遍适用的约束模型，能针对不同的约束需求来进行电容选取，更具有普遍适用性；从模块化多电平控制器的工作入手很好的考虑了其稳定运行和安全运行的约束条件，各模型充分考虑了模块化多电平变换器的安全运行与稳定运行，且最终以三种模型中约束范围最大值作为最终的电容选取条件，更加安全可靠，换流器交直流侧功率传输、直流母线电压支撑得到保障。
优选的，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线。
优选的，所述步骤一中，利用公式
Figure PCTCN2020134887-appb-000001
建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij为子模块SMij的电压；m为调制指数且
Figure PCTCN2020134887-appb-000002
V s为交流侧电压，V dc等 同于U dc；
Figure PCTCN2020134887-appb-000003
表示模块化多电平变换器的功率因素角。
优选的，所述步骤二中，利用公式
Figure PCTCN2020134887-appb-000004
建立最大允许承受超额电压与电容的约束模型；
其中，I S表示交流电流的均方根值，t表示时间，V ex为最大允许承受超额电压且
Figure PCTCN2020134887-appb-000005
V SMdc为半桥电压，V r表示最大可调电压；N表示半桥上子模块的总数，max表示取最大值。
优选的，所述步骤三中，利用公式
Figure PCTCN2020134887-appb-000006
建立子模块电压能力要求与电容的约束模型。
本发明还提供一种模块化多电平变换器直流电容选取装置，所述装置应用于三相电压型模块化多电平变换器的主电路，所述装置包括：
第一模型建立模块，用于建立电容与最大允许波动率的约束模型；
第二模型建立模块，用于建立最大允许承受超额电压与电容的约束模型；
第三模型建立模块，用于建立子模块电压能力要求与电容的约束模型；
电容选取模块，用于综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取。
优选的，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线。
优选的，所述第一模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000007
建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij为子模块SMij的电压；m为调制指数且
Figure PCTCN2020134887-appb-000008
V s为交流侧电压，V dc等同于U dc；
Figure PCTCN2020134887-appb-000009
表示模块化多电平变换器的功率因素角。
优选的，所述第二模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000010
建立最大允许承受超额电压与电容的约束模型；
其中，I S表示交流电流的均方根值，t表示时间，V ex为最大允许承受超额电压且
Figure PCTCN2020134887-appb-000011
V SMdc为半桥电压，V r表示最大可调电压；N表示半桥上子模块的总数，max表示取最大值。
优选的，所述第三模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000012
建立子模块电压能力要求与电容的约束模型。
本发明的优点在于：本发明针对现有技术缺乏一套合理的子模块电容选取方法，建立了普遍适用的约束模型，能针对不同的约束需求来进行电容选取，更具有普遍适用性；从模块化多电平控制器的工作入手很好的考虑了其稳定运行和安全运行的约束条件，各模型充分考虑了模块化多电平变换器的安全运行与稳定运行，且最终以三种模型中约束范围最大值作为最终的电容选取条件，更加安全可靠，换流器交直流侧功率传输、直流母线电压支撑得到保障。
附图说明
图1为本发明实施例所公开的一种模块化多电平变换器直流电容选取方法的流程图；
图2为本发明实施例所公开的一种模块化多电平变换器直流电容选取方法中的三相电压型模块化多电平变换器的主电路的拓扑图；
图3为本发明实施例所公开的一种模块化多电平变换器直流电容选取方法中的三相电压型模块化多电平变换器的主电路中的子模块原理图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例，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作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。
实施例1
如图1所示，一种模块化多电平变换器直流电容选取方法，所述方法应用于三相电压型模块化多电平变换器的主电路，该主电路为现有技术的电路，如图2，为现有技术的一种三相电压型模块化多电平变换器的主电路的拓扑图，其结构为，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，例如图2所示的，每条线上子模块SM1至子模块SMN组成一个半桥，位于整个桥臂上半部的为上半桥，位于整个桥臂下半部的为下半桥，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线，如图2中的phase a表示A相，phase b表示B相，phase c表示C相，ac side表示交流侧，dc side表示直流侧，V SMdc为半桥电压，V dc等同于U dc为直流侧电压，V SMij等同于U SMij为子模块SMij的电压，i arm为支路电流也即每条桥臂的电流。如图3所示为每个子模块的原理图，每个子模块有两个开关管和一个电容组成，一个开关管的发射极连接另一个开关管的集电极，一个开关管的集电极与另一个开关管的发射极之间连接电容，一个开关管的发射极与另一个开关管的集电极之间为该子模块的电压。由于该主电路为现有技术比较常见的 电路，在此不对其电路原理以及详细结构进行描述。
所述方法包括：
步骤S1：建立电容与最大允许波动率的约束模型；具体为：由于子模块内的每个开关管都会单独承受电容电压，过大的电容电压波动不仅影响电容本身耐压值选取，还可能威胁开关器件的安全运行区域，因此在电容的选取过程中最大允许波动率必须得考虑进去。出于换流器安全运行考虑，一般会给定正常运行电容电压最大允许波动率，根据能量变化和实际能量波动的关系利用公式
Figure PCTCN2020134887-appb-000013
建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij为子模块SMij的电压；m为调制指数且
Figure PCTCN2020134887-appb-000014
V s为交流侧电压，V dc等同于U dc；
Figure PCTCN2020134887-appb-000015
表示模块化多电平变换器的功率因素角。该模型在考虑了电容电压波动的情况下，对电容的选取范围做了限定，C Sel1为考虑电容电压波动的情况下的电容值。
步骤S2：建立最大允许承受超额电压与电容的约束模型；具体过程为：在模块化多电平变换器中，每一个子模块的端口输出电压等于模块中电容的电压，为了保证变换器正常运行，在运行过程中，电容电压必须始终低于子模块中各种设备的电压限制，所以有
Figure PCTCN2020134887-appb-000016
V ex为最大允许承受超额电压，V SMdc为半桥电压，V r表示最大可调电压，当然电容允许一定量的超过额定电压，一般称为最大允许承受超额电压。在实际中会给定最大允 许承受超额电压，根据最大允许超额电压大于实际电压的原则，利用公式
Figure PCTCN2020134887-appb-000017
建立最大允许承受超额电压与电容的约束模型；
其中，I S表示交流电流的均方根值，t表示时间；N表示半桥上子模块的总数，max表示取最大值。该模型在考虑了最大允许承受超额电压的情况下，对电容的选取范围做了限定，C Sel2为考虑最大允许承受超额电压的情况下的电容值。
步骤S3：建立子模块电压能力要求与电容的约束模型；具体过程为：为了保证每个桥臂的电压输出能保证持续稳定，对子模块的电压进行一定的限制，即一个桥臂中的总的子模块电容电压必须足以在任何时候合成所需的桥臂电压，以提供所需的伴生相电压，因此利用公式
Figure PCTCN2020134887-appb-000018
建立子模块电压能力要求与电容的约束模型。该模型在考虑了子模块电压能力要求，对电容的选取范围做了限定，C Sel3为考虑子模块电压能力要求的电容值。
步骤S4：综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取，这样选出的电容能够保证电路持续稳定运行，充分考虑了模块化多电平变换器的安全运行，建立了普遍适用的约束模型，能针对不同的约束需求来进行选取，更具有普遍适用性。 例如，当C Sel1的范围为大于6，C Sel2的范围为大于4，C Sel3的范围为大于2时，三种模型中约束范围最大值为大于6，最终的电容选取条件为电容值大于6。
通过以上技术方案，本发明提供的一种模块化多电平变换器直流电容选取方法，主要是针对现有技术缺乏一套合理的子模块电容选取方法，建立了普遍适用的约束模型，能针对不同的约束需求来进行电容选取，更具有普遍适用性；从模块化多电平控制器的工作入手很好的考虑了其稳定运行和安全运行的约束条件，各模型充分考虑了模块化多电平变换器的安全运行与稳定运行，且最终以三种模型中约束范围最大值作为最终的电容选取条件，更加安全可靠，换流器交直流侧功率传输、直流母线电压支撑得到保障。
实施例2
与本发明实施例1相对应的，本发明实施例2还提供一种模块化多电平变换器直流电容选取装置，所述装置应用于三相电压型模块化多电平变换器的主电路，所述装置包括：
第一模型建立模块，用于建立电容与最大允许波动率的约束模型；
第二模型建立模块，用于建立最大允许承受超额电压与电容的约束模型；
第三模型建立模块，用于建立子模块电压能力要求与电容的约束模型；
电容选取模块，用于综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取。
具体的，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线。
具体的，所述第一模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000019
建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij为子模块SMij的电压；m为调制指数且
Figure PCTCN2020134887-appb-000020
V s为交流侧电压，V dc等同于U dc；
Figure PCTCN2020134887-appb-000021
表示模块化多电平变换器的功率因素角。
具体的，所述第二模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000022
建立最大允许承受超额电压与电容的约束模型；
其中，I S表示交流电流的均方根值，t表示时间，V ex为最大允许承受超额电压且
Figure PCTCN2020134887-appb-000023
V SMdc为半桥电压，V r表示最大可调电压；N表示半桥上子模块的总数，max表示取最大值。
具体的，所述第三模型建立模块还用于：利用公式
Figure PCTCN2020134887-appb-000024
建立子模块电压能力要求与电容的约束模型。
以上实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施例对本发明进行了详细的说明，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发明各实施例技术方案的精神和范围。

Claims (10)

  1. 一种模块化多电平变换器直流电容选取方法，其特征在于，所述方法应用于三相电压型模块化多电平变换器的主电路，所述方法包括：
    步骤一：建立电容与最大允许波动率的约束模型；
    步骤二：建立最大允许承受超额电压与电容的约束模型；
    步骤三：建立子模块电压能力要求与电容的约束模型；
    步骤四：综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取。
  2. 根据权利要求1所述的一种模块化多电平变换器直流电容选取方法，其特征在于，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线。
  3. 根据权利要求2所述的一种模块化多电平变换器直流电容选取方法，其特征在于，所述步骤一中，利用公式
    Figure PCTCN2020134887-appb-100001
    建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij 为子模块SMij的电压；m为调制指数且
    Figure PCTCN2020134887-appb-100002
    V s为交流侧电压，V dc等同于U dc；
    Figure PCTCN2020134887-appb-100003
    表示模块化多电平变换器的功率因素角。
  4. 根据权利要求3所述的一种模块化多电平变换器直流电容选取方法，其特征在于，所述步骤二中，利用公式
    Figure PCTCN2020134887-appb-100004
    建立最大允许承受超额电压与电容的约束模型；
    其中，I S表示交流电流的均方根值，t表示时间，V ex为最大允许承受超额电压且
    Figure PCTCN2020134887-appb-100005
    V SMdc为半桥电压，V r表示最大可调电压；N表示半桥上子模块的总数，max表示取最大值。
  5. 根据权利要求4所述的一种模块化多电平变换器直流电容选取方法，其特征在于，所述步骤三中，利用公式
    Figure PCTCN2020134887-appb-100006
    建立子模块电压能力要求与电容的约束模型。
  6. 一种模块化多电平变换器直流电容选取装置，其特征在于，所述装置应用于三相电压型模块化多电平变换器的主电路，所述装置包括：
    第一模型建立模块，用于建立电容与最大允许波动率的约束模型；
    第二模型建立模块，用于建立最大允许承受超额电压与电容的约束模型；
    第三模型建立模块，用于建立子模块电压能力要求与电容的约束模型；
    电容选取模块，用于综合比较电容与最大允许波动率的约束模型、最大允许承受超额电压与电容的约束模型以及子模块电压能力要求与电容的约束模型这三种模型的约束范围，选择三种模型中约束范围最大值作为最终的电容选取条件，依据电容选取条件进行电容选取。
  7. 根据权利要求6所述的一种模块化多电平变换器直流电容选取装置，其特征在于，所述三相电压型模块化多电平变换器的主电路包括三个桥臂，每个桥臂包括上半桥和下半桥，上半桥和下半桥均由N个子模块串联连接而成，所有的上半桥的一端连接到一起形成直流侧电压正极，所有的上半桥的另一端均各自串联连接一个电感，所有的下半桥的一端均各自串联连接另一个电感，每个桥臂的上半桥串联连接的电感与下半桥串联连接的电感连接，所有的下半桥的另一端连接到一起形成直流侧电压负极，每个桥臂的中点均引出导线分别接三相交流电压源的三相线。
  8. 根据权利要求7所述的一种模块化多电平变换器直流电容选取装置，其特征在于，所述第一模型建立模块还用于：利用公式
    Figure PCTCN2020134887-appb-100007
    建立电容与最大允许波动率的约束模型，其中，ω为角频率；ε为最大允许波动率；n为每条桥臂的子模块数量；I dc为直流侧电流；U dc为直流侧电压；U SMij为子模块SMij的电压；m为调制指数且
    Figure PCTCN2020134887-appb-100008
    V s为交流侧电压，V dc等同于U dc；
    Figure PCTCN2020134887-appb-100009
    表示模块化多电平变换器的功率因素角。
  9. 根据权利要求8所述的一种模块化多电平变换器直流电容选取装置，其特征在于，所述第二模型建立模块还用于：利用公式
    Figure PCTCN2020134887-appb-100010
    建立最大允许承受超额电压与电容的约束模型；
    其中，I S表示交流电流的均方根值，t表示时间，V ex为最大允许承受超额电压且
    Figure PCTCN2020134887-appb-100011
    V SMdc为半桥电压，V r表示最大可调电压；N表示半桥上子模块的总数，max表示取最大值。
  10. 根据权利要求9所述的一种模块化多电平变换器直流电容选取装置，其特征在于，所述第三模型建立模块还用于：利用公式
    Figure PCTCN2020134887-appb-100012
    建立子模块电压能力要求与电容的约束模型。
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CN111404412B (zh) * 2020-03-11 2021-07-23 合肥科威尔电源系统股份有限公司 一种模块化多电平变换器直流电容选取方法及装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105006987A (zh) * 2015-07-29 2015-10-28 浙江大学 一种mmc子模块电容值的选取方法
JP2016063610A (ja) * 2014-09-17 2016-04-25 株式会社東芝 電力変換装置
CN106936150A (zh) * 2015-12-30 2017-07-07 中国电力科学研究院 一种模块化多电平直流输电系统的参数优化配置方法
CN107769597A (zh) * 2017-10-17 2018-03-06 清华大学 一种减少模块化多电平换流器所用电容量的方法
CN109149981A (zh) * 2018-08-20 2019-01-04 华中科技大学 一种适用于mmc的基于遗传算法的多目标优化方法
CN111404412A (zh) * 2020-03-11 2020-07-10 合肥科威尔电源系统股份有限公司 一种模块化多电平变换器直流电容选取方法及装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110829477B (zh) * 2019-10-24 2021-05-28 上海交通大学 一种模块化多电平变换器子模块电容最小化优化方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016063610A (ja) * 2014-09-17 2016-04-25 株式会社東芝 電力変換装置
CN105006987A (zh) * 2015-07-29 2015-10-28 浙江大学 一种mmc子模块电容值的选取方法
CN106936150A (zh) * 2015-12-30 2017-07-07 中国电力科学研究院 一种模块化多电平直流输电系统的参数优化配置方法
CN107769597A (zh) * 2017-10-17 2018-03-06 清华大学 一种减少模块化多电平换流器所用电容量的方法
CN109149981A (zh) * 2018-08-20 2019-01-04 华中科技大学 一种适用于mmc的基于遗传算法的多目标优化方法
CN111404412A (zh) * 2020-03-11 2020-07-10 合肥科威尔电源系统股份有限公司 一种模块化多电平变换器直流电容选取方法及装置

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
JIANG HAOYU, LI HUA;YI BOSI;LI LU;CHEN QIREN;LI ZHENG;LIN FUCHANG;CAI WEI;ZHANG HAILONG: "Study on Capacitor Parameters of Flexible HVDC Transmission Project", POWER CAPACITOR & REACTIVE POWER COMPENSATION, vol. 41, no. 1, 1 January 2020 (2020-01-01), pages 102 - 106, XP055854617, ISSN: 1674-1757, DOI: 10.14044/j.1674-1757.pcrpc.2020.01.017 *
LI WEIGUO, QIN JINGMING; CHEN JINGYI;CUI MING: "Selection and Calculation for Sub-module Capacitance and Inductance of Bridge Arm in MMC-HVDC System", JOURNAL OF NORTHEAST DIANLI UNIVERSITY, vol. 39, no. 2, 1 April 2019 (2019-04-01), pages 47 - 53, XP055854623, ISSN: 1005-2992, DOI: 10.19718/j.issn.1005-2992.2019-02-0047-07 *
SHANSHAN WANG, XIAOXIN ZHOU, GUANGFU TANG, ZHIYUAN HE, LETIAN TENG, JUN LIU: "Selection and Calculation for Sub-module Capacitance in Modular Multi-level Converter HVDC Power Transmission System", POWER SYSTEM TECHNOLOGY, SHUILI-DIANLIBU DIANLI KEXUE YANJIUYUAN, BEIJING, CN, vol. 35, no. 1, 31 January 2011 (2011-01-31), CN, pages 26 - 32, XP055854612, ISSN: 1000-3673, DOI: 10.13335/j.1000-3673.pst.2011.01.005 *

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