WO2021217900A1 - Droop control-based method for accurate distribution of reactive power of micro-grid - Google Patents

Droop control-based method for accurate distribution of reactive power of micro-grid Download PDF

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WO2021217900A1
WO2021217900A1 PCT/CN2020/102578 CN2020102578W WO2021217900A1 WO 2021217900 A1 WO2021217900 A1 WO 2021217900A1 CN 2020102578 W CN2020102578 W CN 2020102578W WO 2021217900 A1 WO2021217900 A1 WO 2021217900A1
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inverter
reactive power
voltage
output
droop
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PCT/CN2020/102578
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French (fr)
Chinese (zh)
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吴娜
董龙景
樊淑娴
刘子晖
周成祥
杨征贤
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山东科技大学
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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
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Definitions

  • the invention belongs to the field of power system operation and control, and in particular relates to a microgrid reactive power precise distribution method based on droop control.
  • microgrid can operate in two modes, island and grid-connected, and can switch to each other. Whether it is active islanding or passive islanding, droop control is widely used in microgrids. Since the frequency of each point is the same in the same interconnected system, multiple inverters can be dispatched uniformly according to the frequency; however, the inverter output voltage is a local variable, which will vary with the inverter structure parameters and The distance to the grid connection point changes, which results in different voltage amplitudes at the output terminals of each inverter, which makes it impossible to dispatch multiple inverters in a unified manner, which makes the reactive power output by the inverters unreasonable.
  • the virtual impedance method is used to compensate the impedance difference, but the virtual impedance will cause a voltage drop, the virtual impedance is not easy to choose, and often the system stability and decoupling effects cannot be achieved at the same time, so that the control effect of this method will be greatly limited;
  • the voltage method introduces a compensation coefficient and dynamically adjusts the reference voltage, but it will cause circulation problems;
  • the parallel virtual resistance parallel method makes the inverter equivalent impedance close to equal, and the system stability is enhanced, but it has a greater impact on the inverter output voltage .
  • the present invention provides a method for accurately allocating reactive power of a microgrid based on droop control.
  • a method for precise distribution of reactive power in microgrid based on droop control includes the following steps:
  • Step 1 Collect the voltage and current signals on the AC side of the inverter
  • Step 2 Perform Parker transformation on the collected voltage and current signals
  • Step 3 Use the transformed voltage and current to calculate the power
  • Step 4 Perform droop control
  • Step 5 Decoupling control of the reference voltage calculated after droop control
  • Step 6 Perform counter-Pike transformation on the decoupled voltage to obtain the voltage in the three-phase static coordinate system.
  • Step 7 According to the voltage obtained in step 6, use sine pulse width modulation technology to control the inverter output.
  • step 2 specifically includes:
  • the voltage is expressed in the three-phase stationary coordinate system as:
  • u a , u b , u c are the voltages of the a, b, and c axes in the three-phase static coordinate system
  • U is the voltage amplitude of the inverter output terminal
  • ⁇ is the voltage of the phase a and the a axis of the coordinate system.
  • the voltage is expressed in the two-phase rotating coordinate system as:
  • u d and u q are the voltage components of the d-axis and q-axis in the two-phase rotating coordinate system, respectively, Is the angle between the d-axis of the two-phase rotating coordinate system and the a-axis of the three-phase stationary coordinate system;
  • i d and i q are the current components of the d-axis and q-axis in the two-phase rotating coordinate system
  • i a , i b and i c are the voltages of the a, b, and c-axis in the three-phase stationary coordinate system, respectively Weight.
  • step 3 is specifically:
  • P is the active power output by the inverter
  • Q is the reactive power output by the inverter
  • step 4 specifically includes the following sub-steps:
  • Step 4.1 Calculate the relationship between the inverter output reactive power and the droop coefficient and line impedance according to the droop characteristic curve and the line characteristic curve;
  • Step 4.2 Find the condition that the reactive power output by the inverter is proportional to the rated reactive power of the inverter;
  • Step 4.3 Calculate the reactive power that the inverter should output
  • Step 4.4 Determine whether the calculated reactive power meets the constraints of the inverter
  • Step 4.5 Calculate the inverter reference voltage.
  • step 4.1 is specifically:
  • the inverter voltage amplitude has a linear relationship with the output reactive power, namely:
  • U 0 represents the reference value of the voltage amplitude at the output terminal of the inverter
  • k represents the droop coefficient
  • the change rule of the voltage amplitude at the output terminal of the inverter with the reactive power is:
  • U pcc represents the voltage amplitude of the grid-connected point
  • x represents the line impedance from the inverter to the grid-connected point
  • step 4.2 is specifically:
  • the reactive power output by the inverter is proportional to the rated reactive power as follows:
  • step 4.3 is specifically:
  • the reactive power Q 2 that should be output by any other inverter can be obtained;
  • Step 4.4 is specifically as follows:
  • the inverter’s output reactive power is limited by the inverter’s rated reactive power and grid-connected conditions.
  • the maximum output reactive power must be limited to make Its constant is Q max ;
  • the minimum value of the output reactive power should be limited to make it constant as Q min ;
  • Step 4.5 is specifically as follows:
  • U ref is the reference voltage output by the inverter.
  • step 5 is specifically:
  • the PI controller is used for reference voltage feedforward decoupling, and the control equation is:
  • K P and K I are the proportional and integral gains of the voltage PI regulator, respectively, ⁇ is the angular velocity under the power frequency, L is the inductance, and v d and v q are the decoupled d-axis and q-axis voltage components.
  • step 6 is specifically:
  • step 7 is specifically:
  • the sinusoidal pulse width modulation controller compares the amplitudes of the three-phase voltage signal and the carrier signal in step 6 in real time, and according to the comparison result, sends the "on” and “off” action commands S abc to the switching devices in the inverter , Make the inverter output three-phase AC voltage.
  • This method compensates for the difference in output reactive power caused by different line impedances by adjusting the inverter droop coefficient, so that each inverter can automatically, accurately and quickly adjust the output reactive power according to actual operating conditions, and realize multiple inverters.
  • the output reactive power is reasonably distributed, and the voltage level of the grid connection point is increased at the same time.
  • Figure 1 is the inverter control flow chart.
  • Figure 2 is the inverter droop control flow chart.
  • Figure 3 is a reference voltage decoupling diagram.
  • Step 1 Collect the voltage and current signals on the AC side of the inverter.
  • Step 2 Carry out Parker transformation on the collected voltage and current signals to obtain the dq axis components.
  • the voltage in the three-phase (abc) static coordinate system can be expressed as:
  • u a , u b , u c are the voltages of axis a, b, and c in the three-phase static coordinate system
  • U is the voltage amplitude of the inverter output terminal
  • ⁇ is the voltage of phase a and the axis a of the coordinate system The angle between.
  • the voltage in the two-phase (dq) rotating coordinate system can be expressed as:
  • u d and u q are the voltage components of the d-axis and q-axis in the two-phase rotating coordinate system, respectively, It is the angle between the d-axis of the two-phase rotating coordinate system and the a-axis of the three-phase stationary coordinate system.
  • i d and i q are the current components of the d-axis and q-axis in the two-phase rotating coordinate system
  • i a , i b and i c are the voltages of the a, b, and c-axis in the three-phase stationary coordinate system, respectively Weight.
  • Step 3 Use the transformed voltage and current to calculate the power.
  • P is the active power output by the inverter
  • Q is the reactive power output by the inverter
  • Step 4 Perform droop control.
  • the control flow chart is shown as in Fig. 2.
  • Step 4.1 Calculate the relationship between the inverter output reactive power and the droop coefficient and line impedance according to the droop characteristic curve and the line characteristic curve;
  • the inverter voltage amplitude has a linear relationship with the output reactive power, namely:
  • U 0 represents the reference value of the voltage amplitude at the output terminal of the inverter
  • k represents the droop coefficient
  • the change rule of the voltage amplitude at the output terminal of the inverter with the reactive power is:
  • U pcc represents the voltage amplitude of the grid-connected point
  • x represents the line impedance from the inverter to the grid-connected point
  • Step 4.2 Find the condition that the reactive power output by the inverter is proportional to the rated reactive power of the inverter;
  • the reactive power output by the inverter is proportional to the rated reactive power as follows:
  • Step 4.3 Calculate the reactive power that the inverter should output
  • the reactive power Q 2 that should be output by any other inverter can be obtained;
  • Step 4.4 Judge whether the calculated reactive power Q 2 meets the constraints of the inverter
  • the inverter’s output reactive power is limited by the inverter’s rated reactive power and grid-connected conditions.
  • the maximum output reactive power must be limited to make Its constant is Q max ;
  • the minimum value of the output reactive power should be limited to make it constant as Q min ;
  • Step 4.5 Calculate the inverter reference voltage
  • U ref is the reference voltage output by the inverter.
  • Step 5 Decoupling control is performed on the reference voltage calculated in step 4.5.
  • K P and K I are the proportional and integral gains of the voltage PI regulator, respectively, ⁇ is the angular velocity under the power frequency, L is the inductance, and v d and v q are the decoupled d-axis and q-axis voltage components.
  • the reactive power can be controlled independently by adjusting the voltage d-axis component u d.
  • Step 6 Reverse Parker transformation on v d and v q to obtain the voltage in the three-phase stationary coordinate system
  • Step 7 According to the voltage obtained in step 6, use sine pulse width modulation technology to control the inverter output.
  • the sinusoidal pulse width modulation controller compares the amplitudes of the three-phase voltage signal and the carrier signal in step 6 in real time, and according to the comparison result, sends the "on” and “off” action commands S abc to the switching devices in the inverter , Make the inverter output three-phase AC voltage.

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Abstract

The present invention relates to the field of power system operation and control. Disclosed is a droop control-based method for accurate distribution of reactive power of a micro-grid. A distributed power supply in a micro-grid is mainly connected to a grid by means of an inverter interface, one of a plurality of inverters connected to the same bus in parallel is selected as a main control inverter, and local droop control parameters and line impedance from the inverter to a grid-connected point are transmitted to other inverters by means of a communication network. After other inverters obtain the parameters of the main control inverter, a local droop coefficient is adjusted according to droop control and a line characteristic constraint equation. Finally, the purpose of accurate distribution of reactive power is achieved. Different from conventional successive approximation adjustment, this method directly obtains output reactive power according to the droop control and the line characteristic constraint equation, and is thus simple, quick and reliable.

Description

一种基于下垂控制的微网无功功率精确分配方法An accurate distribution method of reactive power in microgrid based on droop control 技术领域Technical field
本发明属于电力系统运行与控制领域，具体涉及一种基于下垂控制的微网无功功率精确分配方法。The invention belongs to the field of power system operation and control, and in particular relates to a microgrid reactive power precise distribution method based on droop control.
背景技术Background technique
微电网作为一项有效管理和协调逆变器运行的新技术，可以运行在孤岛和并网两种模式，并能相互切换。无论是主动孤岛还是被动孤岛，下垂控制都在微电网中应用广泛。由于各点的频率在同一个互联系统中都是相同的，因此可以根据频率对多个逆变器进行统一调度；但是逆变器输出端电压是一个局部变量，会随逆变器结构参数以及其到并网点距离的不同而发生变化，导致每个逆变器输出端电压幅值各不相同，无法对多个逆变器进行统一调度，使逆变器的输出的无功功率不合理。由于低压微电网中电压等级较低，电压随线路阻抗下降迅速，如果不能合理控制无功功率分配，在极端情况下将会使逆变器输出超出额定功率，造成电压越限，电能质量下降，危害用电设备安全等一系列问题，对生产生活造成不良影响。近年来，国内外学者提出了很多改进的下垂控制的新方法。如采用虚拟阻抗法补偿阻抗差异，但虚拟阻抗会导致电压降落，虚拟阻抗大小不易选取，往往系统稳定和解耦效果两者不可兼得，使得该方法的控制效果将受到很大限制；变参考电压法，引入补偿系数，动态调节参考电压，但会造成环流问题；并联虚拟电阻并联法，使逆变器等效阻抗接近相等，系统稳定性增强，但对逆变器输出端电压影响较大。As a new technology for effectively managing and coordinating the operation of inverters, microgrid can operate in two modes, island and grid-connected, and can switch to each other. Whether it is active islanding or passive islanding, droop control is widely used in microgrids. Since the frequency of each point is the same in the same interconnected system, multiple inverters can be dispatched uniformly according to the frequency; however, the inverter output voltage is a local variable, which will vary with the inverter structure parameters and The distance to the grid connection point changes, which results in different voltage amplitudes at the output terminals of each inverter, which makes it impossible to dispatch multiple inverters in a unified manner, which makes the reactive power output by the inverters unreasonable. Due to the low voltage level in the low-voltage microgrid, the voltage drops rapidly with the line impedance. If the reactive power distribution cannot be controlled reasonably, the inverter output will exceed the rated power in extreme cases, causing the voltage limit to be exceeded and the power quality to decrease. A series of problems, such as endangering the safety of electrical equipment, have a negative impact on production and life. In recent years, domestic and foreign scholars have proposed many new and improved methods for droop control. If the virtual impedance method is used to compensate the impedance difference, but the virtual impedance will cause a voltage drop, the virtual impedance is not easy to choose, and often the system stability and decoupling effects cannot be achieved at the same time, so that the control effect of this method will be greatly limited; The voltage method introduces a compensation coefficient and dynamically adjusts the reference voltage, but it will cause circulation problems; the parallel virtual resistance parallel method makes the inverter equivalent impedance close to equal, and the system stability is enhanced, but it has a greater impact on the inverter output voltage .
发明内容Summary of the invention
针对现有技术存在的缺点，本发明提供了一种基于下垂控制的微网无功功率精确分配方法。Aiming at the shortcomings of the prior art, the present invention provides a method for accurately allocating reactive power of a microgrid based on droop control.
本发明采用以下的技术方案：The present invention adopts the following technical solutions:
一种基于下垂控制的微网无功功率精确分配方法，包括以下步骤：A method for precise distribution of reactive power in microgrid based on droop control includes the following steps:
步骤1：采集逆变器交流侧电压电流信号；Step 1: Collect the voltage and current signals on the AC side of the inverter;
步骤2：对采集到的电压电流信号进行派克变换；Step 2: Perform Parker transformation on the collected voltage and current signals;
步骤3：利用变换后的电压电流计算功率；Step 3: Use the transformed voltage and current to calculate the power;
步骤4：进行下垂控制；Step 4: Perform droop control;
步骤5：对下垂控制后计算的参考电压进行解耦控制；Step 5: Decoupling control of the reference voltage calculated after droop control;
步骤6：对解耦后的电压进行反派克变换，得到三相静止坐标系下的电压。Step 6: Perform counter-Pike transformation on the decoupled voltage to obtain the voltage in the three-phase static coordinate system.
步骤7：根据步骤6得到的电压，利用正弦脉宽调制技术控制逆变器输出。Step 7: According to the voltage obtained in step 6, use sine pulse width modulation technology to control the inverter output.
优选地，步骤2具体为：Preferably, step 2 specifically includes:
派克变换的具体内容为：The specific content of Parker Transformation is:
电压在三相静止坐标系下表示为：The voltage is expressed in the three-phase stationary coordinate system as:
Figure PCTCN2020102578-appb-000001
Figure PCTCN2020102578-appb-000001
其中，u a、u b、u c分别为三相静止坐标系下的a、b、c轴的电压，U为逆变器输出端电压幅值，θ为a相电压与坐标系a轴之间的角度； Among them, u a , u b , u c are the voltages of the a, b, and c axes in the three-phase static coordinate system, U is the voltage amplitude of the inverter output terminal, and θ is the voltage of the phase a and the a axis of the coordinate system. The angle between
电压在两相旋转坐标系下表示为：The voltage is expressed in the two-phase rotating coordinate system as:
Figure PCTCN2020102578-appb-000002
Figure PCTCN2020102578-appb-000002
式中：u d、u q分别为两相旋转坐标系下d轴、q轴的电压分量，
Figure PCTCN2020102578-appb-000003
为两相旋转坐标系d轴与三相静止坐标系a轴之间的角度； Where: u d and u q are the voltage components of the d-axis and q-axis in the two-phase rotating coordinate system, respectively,
Figure PCTCN2020102578-appb-000003
Is the angle between the d-axis of the two-phase rotating coordinate system and the a-axis of the three-phase stationary coordinate system;
由于：due to:
Figure PCTCN2020102578-appb-000004
Figure PCTCN2020102578-appb-000004
以上3个公式联立得：The above 3 formulas are combined:
Figure PCTCN2020102578-appb-000005
Figure PCTCN2020102578-appb-000005
同理电流的派克变换为：In the same way, the Parker transformation of current is:
Figure PCTCN2020102578-appb-000006
Figure PCTCN2020102578-appb-000006
式中：i d、i q分别为两相旋转坐标系下d轴、q轴的电流分量，i a、i b、i c分别为三相静止坐标系下的a、b、c轴的电压分量。 Where: i d and i q are the current components of the d-axis and q-axis in the two-phase rotating coordinate system, and i a , i b and i c are the voltages of the a, b, and c-axis in the three-phase stationary coordinate system, respectively Weight.
优选地，步骤3具体为：Preferably, step 3 is specifically:
基于电压定向的矢量控制策略：Vector control strategy based on voltage orientation:
Figure PCTCN2020102578-appb-000007
Figure PCTCN2020102578-appb-000007
式中：P为逆变器输出的有功功率，Q为逆变器输出的无功功率。Where: P is the active power output by the inverter, and Q is the reactive power output by the inverter.
优选地，步骤4具体包括以下子步骤：Preferably, step 4 specifically includes the following sub-steps:
步骤4.1：根据下垂特性曲线和线路特性曲线计算出逆变器输出无功功率和下垂系数、线路阻抗的关系；Step 4.1: Calculate the relationship between the inverter output reactive power and the droop coefficient and line impedance according to the droop characteristic curve and the line characteristic curve;
步骤4.2：求得逆变器输出的无功功率正比于逆变器额定无功功率的条件；Step 4.2: Find the condition that the reactive power output by the inverter is proportional to the rated reactive power of the inverter;
步骤4.3：计算逆变器应当输出的无功功率；Step 4.3: Calculate the reactive power that the inverter should output;
步骤4.4：判断计算出的无功功率是否满足逆变器的约束条件；Step 4.4: Determine whether the calculated reactive power meets the constraints of the inverter;
步骤4.5：进行逆变器参考电压计算。Step 4.5: Calculate the inverter reference voltage.
优选地，步骤4.1具体为：Preferably, step 4.1 is specifically:
下垂控制策略中逆变器电压幅值和输出无功功率成线性关系，即：In the droop control strategy, the inverter voltage amplitude has a linear relationship with the output reactive power, namely:
U＝U 0-kQ； U=U 0 -kQ;
其中，U 0表示逆变器输出端电压幅值参考值，k表示下垂系数； Among them, U 0 represents the reference value of the voltage amplitude at the output terminal of the inverter, and k represents the droop coefficient;
逆变器输出端电压幅值随无功功率变化规律为：The change rule of the voltage amplitude at the output terminal of the inverter with the reactive power is:
Figure PCTCN2020102578-appb-000008
Figure PCTCN2020102578-appb-000008
其中，U pcc表示并网点电压幅值，x表示逆变器到并网点的线路阻抗； Among them, U pcc represents the voltage amplitude of the grid-connected point, and x represents the line impedance from the inverter to the grid-connected point;
得出逆变器输出无功功率和下垂系数、线路阻抗的关系：Obtain the relationship between the inverter output reactive power, the droop coefficient and the line impedance:
Figure PCTCN2020102578-appb-000009
Figure PCTCN2020102578-appb-000009
优选地，步骤4.2具体为：Preferably, step 4.2 is specifically:
设在同一并网点有多台逆变器，选择其中一个逆变器作为主逆变器，主逆变器的额定无功功率为Q 1'，其它任意一台逆变器的额定无功功率为Q 2'，则 There are multiple inverters at the same grid connection point. Choose one of the inverters as the main inverter, the rated reactive power of the main inverter is Q 1 ', and the rated reactive power of any other inverter Is Q 2 ', then
若主逆变器与任意一台逆变器的额定无功功率的比值为Q 1':Q 2'＝n:1，则对应的下垂系数比值为k 1:k 2＝1:n，因为两台逆变器并联在同一条交流母线上，所以并网点电压U pcc相同，则 逆变器输出的无功功率正比于额定无功功率的条件为： If the ratio of the rated reactive power of the main inverter to any inverter is Q 1 ':Q 2 '=n:1, the corresponding droop coefficient ratio is k 1 :k 2 =1:n, because Two inverters are connected in parallel on the same AC bus, so the grid connection point voltage U pcc is the same, the reactive power output by the inverter is proportional to the rated reactive power as follows:
Figure PCTCN2020102578-appb-000010
Figure PCTCN2020102578-appb-000010
计算出其他任意一台逆变器的下垂系数k 2为： Calculate the droop coefficient k 2 of any other inverter as:
Figure PCTCN2020102578-appb-000011
Figure PCTCN2020102578-appb-000011
优选地，步骤4.3具体为：Preferably, step 4.3 is specifically:
根据步骤4.2得到的下垂系数k 2，能求得其他任意一台逆变器应当输出的无功功率Q 2； According to the droop coefficient k 2 obtained in step 4.2, the reactive power Q 2 that should be output by any other inverter can be obtained;
Figure PCTCN2020102578-appb-000012
Figure PCTCN2020102578-appb-000012
步骤4.4具体为：Step 4.4 is specifically as follows:
逆变器输出无功功率受逆变器额定无功功率和并网条件限制，当计算出的无功功率超出逆变器最大输出无功功率时，要限制输出无功功率的最大值，使其恒定为Q max；当计算出的无功功率低于逆变器最小输出无功功率时，要限制输出无功功率的最小值，使其恒定为Q min； The inverter’s output reactive power is limited by the inverter’s rated reactive power and grid-connected conditions. When the calculated reactive power exceeds the inverter’s maximum output reactive power, the maximum output reactive power must be limited to make Its constant is Q max ; when the calculated reactive power is lower than the minimum output reactive power of the inverter, the minimum value of the output reactive power should be limited to make it constant as Q min ;
Figure PCTCN2020102578-appb-000013
Figure PCTCN2020102578-appb-000013
步骤4.5具体为：Step 4.5 is specifically as follows:
U ref＝U 0-kQ。 U ref =U 0 -kQ.
式中：U ref为逆变器输出的参考电压。 Where: U ref is the reference voltage output by the inverter.
优选地，步骤5具体为：Preferably, step 5 is specifically:
采用PI控制器进行参考电压前馈解耦，控制方程：The PI controller is used for reference voltage feedforward decoupling, and the control equation is:
Figure PCTCN2020102578-appb-000014
Figure PCTCN2020102578-appb-000014
式中：K P、K I分别为电压PI调节器的比例、积分增益，ω为工频下的角速度，L为电感，v d、v q为解耦后的d轴、q轴电压分量。 Where: K P and K I are the proportional and integral gains of the voltage PI regulator, respectively, ω is the angular velocity under the power frequency, L is the inductance, and v d and v q are the decoupled d-axis and q-axis voltage components.
优选地，步骤6具体为：Preferably, step 6 is specifically:
对v d、v q反派克变换为： The villain of v d and v q is transformed into:
Figure PCTCN2020102578-appb-000015
Figure PCTCN2020102578-appb-000015
得到三相静止坐标系下的电压U a、U b和U c。 Obtain the voltages U a , U b and U c in the three-phase stationary coordinate system.
优选地，步骤7具体为：Preferably, step 7 is specifically:
正弦脉宽调制控制器实时地比较步骤6中的三相电压信号和载波信号的幅值大小，根据比较结果，向逆变器中各开关器件发出“通”和“断”的动作指令S abc，使逆变器输出三相交流电压。 The sinusoidal pulse width modulation controller compares the amplitudes of the three-phase voltage signal and the carrier signal in step 6 in real time, and according to the comparison result, sends the "on" and "off" action commands S abc to the switching devices in the inverter , Make the inverter output three-phase AC voltage.
本发明具有的有益效果是：The beneficial effects of the present invention are:
该方法通过调节逆变器下垂系数，补偿线路阻抗不同造成的输出无功功率差异，使各个逆变器可以根据实际运行条件自动、准确、快速地调节输出无功功率，实现多台逆变器输出的无功功率合理分配，同时提高了并网点电压水平。This method compensates for the difference in output reactive power caused by different line impedances by adjusting the inverter droop coefficient, so that each inverter can automatically, accurately and quickly adjust the output reactive power according to actual operating conditions, and realize multiple inverters. The output reactive power is reasonably distributed, and the voltage level of the grid connection point is increased at the same time.
附图说明Description of the drawings
图1为逆变器控制流程图。Figure 1 is the inverter control flow chart.
图2为逆变器下垂控制流程图。Figure 2 is the inverter droop control flow chart.
图3为参考电压解耦图。Figure 3 is a reference voltage decoupling diagram.
具体实施方式Detailed ways
下面结合附图和具体实施例对本发明的具体实施方式做进一步说明：The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:
结合图1至图3，一种基于下垂控制的微网无功功率精确分配方法，其流程如图1所示，包括以下步骤：Combined with Figure 1 to Figure 3, a method for precise distribution of reactive power in microgrid based on droop control. The process is shown in Figure 1, and includes the following steps:
步骤1：采集逆变器交流侧电压电流信号。Step 1: Collect the voltage and current signals on the AC side of the inverter.
步骤2：对采集到的电压电流信号进行派克变换，获取dq轴分量。Step 2: Carry out Parker transformation on the collected voltage and current signals to obtain the dq axis components.
派克变换的具体内容为：The specific content of Parker Transformation is:
电压在三相(abc)静止坐标系下可表示为：The voltage in the three-phase (abc) static coordinate system can be expressed as:
Figure PCTCN2020102578-appb-000016
Figure PCTCN2020102578-appb-000016
式中：u a、u b、u c分别为三相静止坐标系下的a、b、c轴的电压，U为逆变器输出端电压幅值，θ为a相电压与坐标系a轴之间的角度。 In the formula: u a , u b , u c are the voltages of axis a, b, and c in the three-phase static coordinate system, U is the voltage amplitude of the inverter output terminal, and θ is the voltage of phase a and the axis a of the coordinate system The angle between.
电压在两相(dq)旋转坐标系下可表示为：The voltage in the two-phase (dq) rotating coordinate system can be expressed as:
Figure PCTCN2020102578-appb-000017
Figure PCTCN2020102578-appb-000017
式中：u d、u q分别为两相旋转坐标系下d轴、q轴的电压分量，
Figure PCTCN2020102578-appb-000018
为两相旋转坐标系d轴与三相静止坐标系a轴之间的角度。 Where: u d and u q are the voltage components of the d-axis and q-axis in the two-phase rotating coordinate system, respectively,
Figure PCTCN2020102578-appb-000018
It is the angle between the d-axis of the two-phase rotating coordinate system and the a-axis of the three-phase stationary coordinate system.
由于：due to:
Figure PCTCN2020102578-appb-000019
Figure PCTCN2020102578-appb-000019
以上3个公式联立得：The above 3 formulas are combined:
Figure PCTCN2020102578-appb-000020
Figure PCTCN2020102578-appb-000020
同理电流的派克变换为：In the same way, the Parker transformation of current is:
Figure PCTCN2020102578-appb-000021
Figure PCTCN2020102578-appb-000021
式中：i d、i q分别为两相旋转坐标系下d轴、q轴的电流分量，i a、i b、i c分别为三相静止坐标系下的a、b、c轴的电压分量。 Where: i d and i q are the current components of the d-axis and q-axis in the two-phase rotating coordinate system, and i a , i b and i c are the voltages of the a, b, and c-axis in the three-phase stationary coordinate system, respectively Weight.
步骤3：利用变换后的电压电流计算功率。Step 3: Use the transformed voltage and current to calculate the power.
基于电压定向的矢量控制策略：Vector control strategy based on voltage orientation:
Figure PCTCN2020102578-appb-000022
Figure PCTCN2020102578-appb-000022
式中：P为逆变器输出的有功功率，Q为逆变器输出的无功功率。Where: P is the active power output by the inverter, and Q is the reactive power output by the inverter.
步骤4：进行下垂控制。控制流程图如图2所示。Step 4: Perform droop control. The control flow chart is shown as in Fig. 2.
具体包括以下子步骤：Specifically, it includes the following sub-steps:
步骤4.1：根据下垂特性曲线和线路特性曲线计算出逆变器输出无功功率和下垂系数、线路阻抗的关系；Step 4.1: Calculate the relationship between the inverter output reactive power and the droop coefficient and line impedance according to the droop characteristic curve and the line characteristic curve;
下垂控制策略中逆变器电压幅值和输出无功功率成线性关系，即：In the droop control strategy, the inverter voltage amplitude has a linear relationship with the output reactive power, namely:
U＝U 0-kQ； U=U 0 -kQ;
其中，U 0表示逆变器输出端电压幅值参考值，k表示下垂系数； Among them, U 0 represents the reference value of the voltage amplitude at the output terminal of the inverter, and k represents the droop coefficient;
逆变器输出端电压幅值随无功功率变化规律为：The change rule of the voltage amplitude at the output terminal of the inverter with the reactive power is:
Figure PCTCN2020102578-appb-000023
Figure PCTCN2020102578-appb-000023
其中，U pcc表示并网点电压幅值，x表示逆变器到并网点的线路阻抗； Among them, U pcc represents the voltage amplitude of the grid-connected point, and x represents the line impedance from the inverter to the grid-connected point;
得出逆变器输出无功功率和下垂系数、线路阻抗的关系：Obtain the relationship between the inverter output reactive power, the droop coefficient and the line impedance:
Figure PCTCN2020102578-appb-000024
Figure PCTCN2020102578-appb-000024
步骤4.2：求得逆变器输出的无功功率正比于逆变器额定无功功率的条件；Step 4.2: Find the condition that the reactive power output by the inverter is proportional to the rated reactive power of the inverter;
设在同一并网点有多台逆变器，选择其中一个逆变器作为主逆变器，主逆变器的额定无功功率为Q 1'，其它任意一台逆变器的额定无功功率为Q 2'，则 There are multiple inverters at the same grid connection point. Choose one of the inverters as the main inverter, the rated reactive power of the main inverter is Q 1 ', and the rated reactive power of any other inverter Is Q 2 ', then
若主逆变器与任意一台逆变器的额定无功功率的比值为Q 1':Q 2'＝n:1，则对应的下垂系数比值为k 1:k 2＝1:n，因为两台逆变器并联在同一条交流母线上，所以并网点电压U pcc相同，则逆变器输出的无功功率正比于额定无功功率的条件为： If the ratio of the rated reactive power of the main inverter to any inverter is Q 1 ':Q 2 '=n:1, the corresponding droop coefficient ratio is k 1 :k 2 =1:n, because Two inverters are connected in parallel on the same AC bus, so the grid connection point voltage U pcc is the same, the reactive power output by the inverter is proportional to the rated reactive power as follows:
Figure PCTCN2020102578-appb-000025
Figure PCTCN2020102578-appb-000025
计算出其他任意一台逆变器的下垂系数k 2为： Calculate the droop coefficient k 2 of any other inverter as:
Figure PCTCN2020102578-appb-000026
Figure PCTCN2020102578-appb-000026
步骤4.3：计算逆变器应当输出的无功功率；Step 4.3: Calculate the reactive power that the inverter should output;
根据步骤4.2得到的下垂系数k 2，能求得其他任意一台逆变器应当输出的无功功率Q 2； According to the droop coefficient k 2 obtained in step 4.2, the reactive power Q 2 that should be output by any other inverter can be obtained;
Figure PCTCN2020102578-appb-000027
Figure PCTCN2020102578-appb-000027
步骤4.4：判断计算出的无功功率Q 2是否满足逆变器的约束条件； Step 4.4: Judge whether the calculated reactive power Q 2 meets the constraints of the inverter;
逆变器输出无功功率受逆变器额定无功功率和并网条件限制，当计算出的无功功率超出逆变器最大输出无功功率时，要限制输出无功功率的最大值，使其恒定为Q max；当计算出的无功功率低于逆变器最小输出无功功率时，要限制输出无功功率的最小值，使其恒定为Q min； The inverter’s output reactive power is limited by the inverter’s rated reactive power and grid-connected conditions. When the calculated reactive power exceeds the inverter’s maximum output reactive power, the maximum output reactive power must be limited to make Its constant is Q max ; when the calculated reactive power is lower than the minimum output reactive power of the inverter, the minimum value of the output reactive power should be limited to make it constant as Q min ;
Figure PCTCN2020102578-appb-000028
Figure PCTCN2020102578-appb-000028
步骤4.5：进行逆变器参考电压计算；Step 4.5: Calculate the inverter reference voltage;
U ref＝U 0-kQ U ref = U 0 -kQ
式中：U ref为逆变器输出的参考电压。 Where: U ref is the reference voltage output by the inverter.
步骤5：对步骤4.5计算到的参考电压进行解耦控制。Step 5: Decoupling control is performed on the reference voltage calculated in step 4.5.
为了实现有功功率、无功功率的独立控制和d、q轴电压大小的独立调节，必须对参考电压进行解耦。因此常采用PI控制器进行电压前馈解耦，解耦框图如图3所示，控制方程：In order to realize the independent control of active power and reactive power and the independent adjustment of the d and q axis voltages, the reference voltage must be decoupled. Therefore, PI controllers are often used for voltage feedforward decoupling. The decoupling block diagram is shown in Figure 3. The control equation:
Figure PCTCN2020102578-appb-000029
Figure PCTCN2020102578-appb-000029
式中：K P、K I分别为电压PI调节器的比例、积分增益，ω为工频下的角速度，L为电感，v d、v q为解耦后的d轴、q轴电压分量。 Where: K P and K I are the proportional and integral gains of the voltage PI regulator, respectively, ω is the angular velocity under the power frequency, L is the inductance, and v d and v q are the decoupled d-axis and q-axis voltage components.
通过引入电流状态反馈，增加电网电压前馈补偿，实现调节电压d轴分量u d就能独立控制无功功率。 By introducing current state feedback and increasing grid voltage feed-forward compensation, the reactive power can be controlled independently by adjusting the voltage d-axis component u d.
步骤6：对v d、v q反派克变换，得到三相静止坐标系下的电压； Step 6: Reverse Parker transformation on v d and v q to obtain the voltage in the three-phase stationary coordinate system;
对v d、v q反派克变换为： The villain of v d and v q is transformed into:
Figure PCTCN2020102578-appb-000030
Figure PCTCN2020102578-appb-000030
得到三相静止坐标系下的电压U a、U b和U c。 Obtain the voltages U a , U b and U c in the three-phase stationary coordinate system.
步骤7：根据步骤6得到的电压，利用正弦脉宽调制技术控制逆变器输出。Step 7: According to the voltage obtained in step 6, use sine pulse width modulation technology to control the inverter output.
具体为：Specifically:
正弦脉宽调制控制器实时地比较步骤6中的三相电压信号和载波信号的幅值大小，根据比较结果，向逆变器中各开关器件发出“通”和“断”的动作指令S abc，使逆变器输出三相交流电压。 The sinusoidal pulse width modulation controller compares the amplitudes of the three-phase voltage signal and the carrier signal in step 6 in real time, and according to the comparison result, sends the "on" and "off" action commands S abc to the switching devices in the inverter , Make the inverter output three-phase AC voltage.
当然，上述说明并非是对本发明的限制，本发明也并不仅限于上述举例，本技术领域的技术人员在本发明的实质范围内所做出的变化、改型、添加或替换，也应属于本发明的保护范围。Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present invention shall also belong to the present invention. The scope of protection of the invention.

Claims (10)

  1. 一种基于下垂控制的微网无功功率精确分配方法，其特征在于，包括以下步骤：A method for precise distribution of reactive power in a microgrid based on droop control is characterized in that it includes the following steps:
    步骤1：采集逆变器交流侧电压电流信号；Step 1: Collect the voltage and current signals on the AC side of the inverter;
    步骤2：对采集到的电压电流信号进行派克变换；Step 2: Perform Parker transformation on the collected voltage and current signals;
    步骤3：利用变换后的电压电流计算功率；Step 3: Use the transformed voltage and current to calculate the power;
    步骤4：进行下垂控制；Step 4: Perform droop control;
    步骤5：对下垂控制后计算的参考电压进行解耦控制；Step 5: Decoupling control of the reference voltage calculated after droop control;
    步骤6：对解耦后的电压进行反派克变换，得到三相静止坐标系下的电压；Step 6: Perform counter-Pike transformation on the decoupled voltage to obtain the voltage in the three-phase static coordinate system;
    步骤7：根据步骤6得到的电压，利用正弦脉宽调制技术控制逆变器输出。Step 7: According to the voltage obtained in step 6, use sine pulse width modulation technology to control the inverter output.
  2. 根据权利要求1所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤2具体为：The method for accurately distributing reactive power of a microgrid based on droop control according to claim 1, wherein step 2 is specifically:
    派克变换的具体内容为：The specific content of Parker Transformation is:
    电压在三相静止坐标系下表示为：The voltage is expressed in the three-phase stationary coordinate system as:
    Figure PCTCN2020102578-appb-100001
    Figure PCTCN2020102578-appb-100001
    其中，u a、u b、u c分别为三相静止坐标系下的a、b、c轴的电压，U为逆变器输出端电压幅值，θ为a相电压与坐标系a轴之间的角度； Among them, u a , u b , u c are the voltages of the a, b, and c axes in the three-phase static coordinate system, U is the voltage amplitude of the inverter output terminal, and θ is the voltage of the phase a and the a axis of the coordinate system. The angle between
    电压在两相旋转坐标系下表示为：The voltage is expressed in the two-phase rotating coordinate system as:
    Figure PCTCN2020102578-appb-100002
    Figure PCTCN2020102578-appb-100002
    式中：u d、u q分别为两相旋转坐标系下d轴、q轴的电压分量，
    Figure PCTCN2020102578-appb-100003
    为两相旋转坐标系d轴与三相静止坐标系a轴之间的角度；     Where: u d and u q are the voltage components of the d-axis and q-axis in the two-phase rotating coordinate system, respectively,
    Figure PCTCN2020102578-appb-100003
    Is the angle between the d-axis of the two-phase rotating coordinate system and the a-axis of the three-phase stationary coordinate system;
    由于：due to:
    Figure PCTCN2020102578-appb-100004
    Figure PCTCN2020102578-appb-100004
    以上3个公式联立得：The above 3 formulas are combined:
    Figure PCTCN2020102578-appb-100005
    Figure PCTCN2020102578-appb-100005
    同理电流的派克变换为：In the same way, the Parker transformation of current is:
    Figure PCTCN2020102578-appb-100006
    Figure PCTCN2020102578-appb-100006
    式中：i d、i q分别为两相旋转坐标系下d轴、q轴的电流分量，i a、i b、i c分别为三相静止坐标系下的a、b、c轴的电压分量。 Where: i d and i q are the current components of the d-axis and q-axis in the two-phase rotating coordinate system, and i a , i b and i c are the voltages of the a, b, and c-axis in the three-phase stationary coordinate system, respectively Weight.
  3. 根据权利要求1所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，A method for precise distribution of reactive power in a microgrid based on droop control according to claim 1, characterized in that:
    步骤3具体为：Step 3 specifically is:
    基于电压定向的矢量控制策略：Vector control strategy based on voltage orientation:
    Figure PCTCN2020102578-appb-100007
    Figure PCTCN2020102578-appb-100007
    式中：P为逆变器输出的有功功率，Q为逆变器输出的无功功率。Where: P is the active power output by the inverter, and Q is the reactive power output by the inverter.
  4. 根据权利要求1所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤4具体包括以下子步骤：A method for precise distribution of reactive power in a microgrid based on droop control according to claim 1, wherein step 4 specifically includes the following sub-steps:
    步骤4.1：根据下垂特性曲线和线路特性曲线计算出逆变器输出无功功率和下垂系数、线路阻抗的关系；Step 4.1: Calculate the relationship between the inverter output reactive power and the droop coefficient and line impedance according to the droop characteristic curve and the line characteristic curve;
    步骤4.2：求得逆变器输出的无功功率正比于逆变器额定无功功率的条件；Step 4.2: Find the condition that the reactive power output by the inverter is proportional to the rated reactive power of the inverter;
    步骤4.3：计算逆变器应当输出的无功功率；Step 4.3: Calculate the reactive power that the inverter should output;
    步骤4.4：判断计算出的无功功率是否满足逆变器的约束条件；Step 4.4: Determine whether the calculated reactive power meets the constraints of the inverter;
    步骤4.5：进行逆变器参考电压计算。Step 4.5: Calculate the inverter reference voltage.
  5. 根据权利要求4所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤4.1具体为：A method for precise distribution of reactive power in a microgrid based on droop control according to claim 4, wherein step 4.1 is specifically:
    下垂控制策略中逆变器电压幅值和输出无功功率成线性关系，即：In the droop control strategy, the inverter voltage amplitude has a linear relationship with the output reactive power, namely:
    U＝U 0-kQ； U=U 0 -kQ;
    其中，U 0表示逆变器输出端电压幅值参考值，k表示下垂系数； Among them, U 0 represents the reference value of the voltage amplitude at the output terminal of the inverter, and k represents the droop coefficient;
    逆变器输出端电压幅值随无功功率变化规律为：The change rule of the voltage amplitude at the output terminal of the inverter with the reactive power is:
    Figure PCTCN2020102578-appb-100008
    Figure PCTCN2020102578-appb-100008
    其中，U pcc表示并网点电压幅值，x表示逆变器到并网点的线路阻抗； Among them, U pcc represents the voltage amplitude of the grid-connected point, and x represents the line impedance from the inverter to the grid-connected point;
    得出逆变器输出无功功率和下垂系数、线路阻抗的关系：Obtain the relationship between the inverter output reactive power, the droop coefficient and the line impedance:
    Figure PCTCN2020102578-appb-100009
    Figure PCTCN2020102578-appb-100009
  6. 根据权利要求5所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤4.2具体为：A method for precise distribution of reactive power in a microgrid based on droop control according to claim 5, wherein step 4.2 is specifically:
    设在同一并网点有多台逆变器，选择其中一个逆变器作为主逆变器，主逆变器的额定无功功率为Q 1'，其它任意一台逆变器的额定无功功率为Q 2'，则 There are multiple inverters at the same grid connection point. Choose one of the inverters as the main inverter, the rated reactive power of the main inverter is Q 1 ', and the rated reactive power of any other inverter Is Q 2 ', then
    若主逆变器与任意一台逆变器的额定无功功率的比值为Q 1':Q 2'＝n:1，则对应的下垂系数比值为k 1:k 2＝1:n，因为两台逆变器并联在同一条交流母线上，所以并网点电压U pcc相同，则逆变器输出的无功功率正比于额定无功功率的条件为： If the ratio of the rated reactive power of the main inverter to any inverter is Q 1 ':Q 2 '=n:1, the corresponding droop coefficient ratio is k 1 :k 2 =1:n, because Two inverters are connected in parallel on the same AC bus, so the grid connection point voltage U pcc is the same, the reactive power output by the inverter is proportional to the rated reactive power as follows:
    Figure PCTCN2020102578-appb-100010
    Figure PCTCN2020102578-appb-100010
    计算出其他任意一台逆变器的下垂系数k 2为： Calculate the droop coefficient k 2 of any other inverter as:
    Figure PCTCN2020102578-appb-100011
    Figure PCTCN2020102578-appb-100011
  7. 根据权利要求6所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤4.3具体为：A method for precise distribution of reactive power in a microgrid based on droop control according to claim 6, wherein step 4.3 is specifically:
    根据步骤4.2得到的下垂系数k 2，能求得其他任意一台逆变器应当输出的无功功率Q 2； According to the droop coefficient k 2 obtained in step 4.2, the reactive power Q 2 that should be output by any other inverter can be obtained;
    Figure PCTCN2020102578-appb-100012
    Figure PCTCN2020102578-appb-100012
    步骤4.4具体为：Step 4.4 is specifically as follows:
    逆变器输出无功功率受逆变器额定无功功率和并网条件限制，当计算出的无功功率超出逆变器最大输出无功功率时，要限制输出无功功率的最大值，使其恒定为Q max；当计算出的无功功率低于逆变器最小输出无功功率时，要限制输出无功功率的最小值，使其恒定为Q min； The inverter’s output reactive power is limited by the inverter’s rated reactive power and grid-connected conditions. When the calculated reactive power exceeds the inverter’s maximum output reactive power, the maximum output reactive power must be limited to make Its constant is Q max ; when the calculated reactive power is lower than the minimum output reactive power of the inverter, the minimum value of the output reactive power should be limited to make it constant as Q min ;
    Figure PCTCN2020102578-appb-100013
    Figure PCTCN2020102578-appb-100013
    步骤4.5具体为：Step 4.5 is specifically as follows:
    U ref＝U 0-kQ。 U ref =U 0 -kQ.
    式中：U ref为逆变器输出的参考电压。 Where: U ref is the reference voltage output by the inverter.
  8. 根据权利要求7所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，The method for precise distribution of reactive power of microgrid based on droop control according to claim 7, characterized in that:
    步骤5具体为：Step 5 is specifically:
    采用PI控制器进行参考电压前馈解耦，控制方程：The PI controller is used for reference voltage feedforward decoupling, and the control equation is:
    Figure PCTCN2020102578-appb-100014
    Figure PCTCN2020102578-appb-100014
    式中：K P、K I分别为电压PI调节器的比例、积分增益，ω为工频下的角速度，L为电感，v d、v q为解耦后的d轴、q轴电压分量。 Where: K P and K I are the proportional and integral gains of the voltage PI regulator, respectively, ω is the angular velocity at the power frequency, L is the inductance, and v d and v q are the decoupled d-axis and q-axis voltage components.
  9. 根据权利要求8所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，A method for precise distribution of reactive power in a microgrid based on droop control according to claim 8, characterized in that:
    步骤6具体为：Step 6 specifically is:
    对v d、v q反派克变换为： The villain of v d and v q is transformed into:
    Figure PCTCN2020102578-appb-100015
    Figure PCTCN2020102578-appb-100015
    得到三相静止坐标系下的电压U a、U b和U c。 Obtain the voltages U a , U b and U c in the three-phase stationary coordinate system.
  10. 根据权利要求9所述的一种基于下垂控制的微网无功功率精确分配方法，其特征在于，步骤7具体为：The method for precise distribution of reactive power in a microgrid based on droop control according to claim 9, wherein step 7 is specifically:
    正弦脉宽调制控制器实时地比较步骤6中的三相电压信号和载波信号的幅值大小，根据比较结果，向逆变器中各开关器件发出“通”和“断”的动作指令S abc，使逆变器输出三相交流电压。 The sinusoidal pulse width modulation controller compares the amplitudes of the three-phase voltage signal and the carrier signal in step 6 in real time, and according to the comparison result, sends "on" and "off" action commands S abc to each switching device in the inverter , Make the inverter output three-phase AC voltage.
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