CN114915195A - Grid-connected harmonic suppression method based on single-phase current source type five-level inverter - Google Patents

Grid-connected harmonic suppression method based on single-phase current source type five-level inverter Download PDF

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CN114915195A
CN114915195A CN202111542621.9A CN202111542621A CN114915195A CN 114915195 A CN114915195 A CN 114915195A CN 202111542621 A CN202111542621 A CN 202111542621A CN 114915195 A CN114915195 A CN 114915195A
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鲍建宇
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Ningbo University of Technology
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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
    • 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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
    • 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
    • H02J3/381—Dispersed generators
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from AC input or output
    • H02M1/126—Arrangements for reducing harmonics from AC input or output using passive filters
    • 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
    • Y02E40/40—Arrangements for reducing harmonics

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  • Power Engineering (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention relates to a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter, which is used for sampling capacitor voltage u c To obtain the capacitor voltage u c Fundamental component u of cb (ii) a Judging a grid-connected mode through a high-frequency harmonic current compensation circuit, and selecting a feedback current i to be constructed according to the grid-connected mode RC (ii) a The obtained sine modulation signal i s * Into a multi-carrier PWM generator, thenAnd then controlling the on and off of each switching device in the single-phase current type five-level inverter circuit. The method performs resonance suppression aiming at an active mode, a reactive mode and the active and reactive modes, so that the effect of adjusting any power factor during grid connection is realized, the functions are rich, the applicability is wider, the method ensures high current response speed, further ensures the corresponding speed of the system, and improves the efficiency.

Description

一种基于单相电流源型五电平逆变器的并网谐波抑制方法A grid-connected harmonic suppression method based on single-phase current source five-level inverter

技术领域technical field

本发明涉及电力电子变流器技术领域，尤其是涉及一种基于单相电流源型五电平逆变器的并网谐波抑制方法。The invention relates to the technical field of power electronic converters, in particular to a grid-connected harmonic suppression method based on a single-phase current source five-level inverter.

背景技术Background technique

根据逆变器直流侧储能元件的不同，并网逆变器可分为电压源型逆变器和电流源型逆变器。目前，并网逆变器普遍采用电压源型逆变器，但电流源型逆变器自身也具有诸多优点，如输入端无需采用电解电容可增加变流器寿命、不存在桥臂直通过流问题、短路保护能力强。采用电流源型五电平逆变器可使输出电流波形更接近正弦，同时每个开关器件只需承受一半电流应力，有效提升电路性能和可靠性。然而，电流源型逆变器在并网时其输出侧通常采用电容滤波，由于并网点跟逆变器输出点连接线之间存在一个等效电感，当该等效电感的感抗刚好达到与逆变器LC谐振时，逆变器输出侧的电网电压会引入一个高频谐振分量，一旦该高频分量经采样进入控制系统，就会导致系统发散、逆变器谐振等问题，如不加抑制则有可能无限放大相频率的谐波电流直至系统崩溃。According to the different energy storage elements on the DC side of the inverter, grid-connected inverters can be divided into voltage source inverters and current source inverters. At present, grid-connected inverters generally use voltage source inverters, but current source inverters also have many advantages. Problems, short circuit protection ability is strong. The use of a current source five-level inverter can make the output current waveform closer to sinusoidal, and each switching device only needs to bear half the current stress, which effectively improves the circuit performance and reliability. However, when the current source inverter is connected to the grid, the output side usually uses capacitor filtering. Since there is an equivalent inductance between the grid connection point and the inverter output point connection line, when the inductive reactance of the equivalent inductance just reaches the When the inverter LC resonates, the grid voltage on the output side of the inverter will introduce a high-frequency resonance component. Once the high-frequency component is sampled into the control system, it will cause problems such as system divergence and inverter resonance. Suppression makes it possible to infinitely amplify harmonic currents at phase frequencies until the system collapses.

现有技术中，一般只针对电压型并网逆变器的谐振进行抑制，抑制方法又是往往仅适合于纯有功并网模式，导致功率因数不可调、功能相对比较单一；另外，现有的针对电压型逆变器的谐振抑制方法通常需要电流和电压的两级变换处理，结构复杂、电流响应速度较慢。In the prior art, only the resonance of the voltage-type grid-connected inverter is generally suppressed, and the suppression method is often only suitable for the pure active grid-connected mode, resulting in an unadjustable power factor and relatively simple functions; The resonance suppression method for the voltage-based inverter usually requires two-stage conversion processing of current and voltage, which has a complex structure and a slow current response speed.

发明内容SUMMARY OF THE INVENTION

本发明所要解决的技术问题是针对单相电流源型五电平逆变器用于并网逆变时所产生的谐振问题，提供一种能够良好地抑制谐振、并网时任意功率因数可调，并且电流响应速度快的并网谐波抑制方法。The technical problem to be solved by the present invention is to provide a system that can well suppress resonance and can adjust any power factor during grid connection, aiming at the resonance problem generated when a single-phase current source five-level inverter is used for grid-connected inverter. And the grid-connected harmonic suppression method with fast current response speed.

本发明所采用的技术方案是，一种基于单相电流源型五电平逆变器的并网谐波抑制方法，该方法通过基于小均流电感单相电流型五电平逆变器的并网系统实施，所述基于小均流电感单相电流型五电平逆变器的并网系统包括主电路部分以及控制电路部分，所述主电路部分包括单相电流型五电平逆变电路、CLL滤波电路以及网侧电源电路，所述控制电路部分包括锁相环电路、单相交流电流的坐标变换电路、基于PI的直接电流控制电路、电容反馈电压的低通滤波处理电路、高频谐波电流补偿电路、并网电流参考信号电路以及多载波PWM发生器驱动电路，所述基于PI的直接电流控制电路包括一级PI调节器，该方法包括下列步骤：The technical solution adopted in the present invention is a grid-connected harmonic suppression method based on a single-phase current source five-level inverter. The grid-connected system is implemented. The grid-connected system based on a single-phase current-type five-level inverter with a small current sharing inductance includes a main circuit part and a control circuit part, and the main circuit part includes a single-phase current-type five-level inverter. Circuit, CLL filter circuit and grid-side power supply circuit, the control circuit part includes a phase-locked loop circuit, a coordinate transformation circuit for single-phase AC current, a direct current control circuit based on PI, a low-pass filter processing circuit for capacitor feedback voltage, high A frequency harmonic current compensation circuit, a grid-connected current reference signal circuit and a multi-carrier PWM generator drive circuit, the PI-based direct current control circuit includes a first-stage PI regulator, and the method includes the following steps:

S1、采集电网电压us作为参考信号，通过锁相环电路进行锁相处理后得到参考相位角θ，将参考相位角θ分别送入单相交流电流的坐标变换电路和基于PI的直接电流控制电路，分别用于αβ-dq变换和dq-αβ变换；S1. Collect the grid voltage u s as the reference signal, obtain the reference phase angle θ after phase-locking processing by the phase-locked loop circuit, and send the reference phase angle θ to the coordinate transformation circuit of single-phase AC current and the direct current control based on PI respectively. Circuits for αβ-dq transformation and dq-αβ transformation;

S2、采集电网电流is，通过单相交流电流的坐标变换电路进行αβ-dq变换处理，获得dq坐标系下的直流电流Id和Iq，并将直流电流Id和Iq送入基于PI的直接电流控制电路作为一级PI调节器的负反馈信号；S2. Collect the grid current is, and perform αβ-dq transformation processing through the coordinate transformation circuit of single-phase AC current to obtain the DC currents I d and I q in the dq coordinate system, and send the DC currents I d and I q to the The direct current control circuit of PI is used as the negative feedback signal of the first-stage PI regulator;

S3、设定理论值Id *和Iq *，Id *表示需向电网注入的有功电流值，Iq *表示需向电网注入的无功电流值，将Id *和Iq *输入基于PI的直接电流控制电路中，分别与负反馈信号Id和Iq进行比较，比较后获得各自的电流误差信号，将电流误差信号输入一级PI调节器进行电流变换，得到新的d-q轴直流电流Isd和Isq，再经dq-αβ反变换后得到单相交流电流isa；S3. Set the theoretical values I d * and I q * , I d * represents the active current value to be injected into the grid, I q * represents the reactive current value to be injected into the grid, input I d * and I q * In the direct current control circuit based on PI, the negative feedback signals I d and I q are compared respectively, and the respective current error signals are obtained after the comparison. DC currents I sd and I sq , and then through dq-αβ inverse transformation to obtain single-phase AC current isa ;

S4、采样电容电压uc，经过处理得到电容电压uc的基波分量ucb；S4, sampling the capacitor voltage uc, and obtaining the fundamental wave component ucb of the capacitor voltage uc after processing ;

S5、通过高频谐波电流补偿电路中有功电流和无功电流的给定值来判断并网模式，并根据并网模式来选择需要构建的反馈电流iRC；具体过程为：当Id *≠0、Iq *＝0时，即以纯有功模式并网，选择电容电压uc作为反馈电流iRC；当Id *＝0、Iq *≠0时，即以纯无功模式并网，选择电容电压uc的高频谐波分量作为反馈电流iRC；当Id *≠0、Iq *≠0时，即以有功+无功模式并网，选择电容电压uc的高频谐波分量作为反馈电流iRC；S5. Judge the grid-connected mode by the given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and select the feedback current i RC to be constructed according to the grid-connected mode; the specific process is: when I d * ≠ 0, I q * = 0, that is, it is connected to the grid in pure active mode, and the capacitor voltage uc is selected as the feedback current i RC ; Select the high-frequency harmonic component of the capacitor voltage uc as the feedback current i RC ; when I d * ≠ 0, I q * ≠ 0, that is, grid-connected in active + reactive mode, select the high-frequency harmonic of the capacitor voltage u c . wave component as feedback current i RC ;

S6、在获得单相交流电流isa的基础上，通过往基于PI的直接电流控制电路中反向注入谐波补偿电流iRC与单相交流电流isa进行比较，比较后获得新的交流电流is ’，经幅值标幺化处理后得到正弦调制信号is *，即并网电流参考信号；S6. On the basis of obtaining the single-phase AC current isa , compare the harmonic compensation current i RC with the single-phase AC current isa by reversely injecting the harmonic compensation current i RC into the direct current control circuit based on PI, and obtain a new AC current after the comparison i s ' , the sinusoidal modulation signal i s * is obtained after the amplitude per-unitization process, that is, the grid-connected current reference signal;

S7、将得到的正弦调制信号is *送入多载波PWM发生器产生8路SPWM信号，经隔离驱动后控制单相电流型五电平逆变电路中的各个开关器件的开通与关断。S7. Send the obtained sinusoidal modulation signal i s * into the multi-carrier PWM generator to generate 8 channels of SPWM signals, and control the opening and closing of each switching device in the single-phase current type five-level inverter circuit after isolation and driving.

本发明的有益效果是：本发明在通用型单相电流型五电平逆变电路拓扑基础上，通过高频调制可将均流电感值从mH级减少到uH级，有效提升了电流型多电平变流器的实用性。本发明将基于uH级均流电感的单相电流源型五电平变流器用于并网逆变，与传统电压型逆变器一样也会产生输出侧的谐波自谐振问题。本发明通过采用高频谐波电流补偿的方法不仅解决了纯有功并网模式(功率因数为1)时的谐波自谐振问题，而且还提供了纯无功以及有功+无功这两种模式下的谐振抑制方法，从而实现了并网时任意功率因数可调的效果。因此，本发明所提的单相电流源型五电平变流器及其谐波抑制策略除了用于常规的并网发电，还具有无功补偿功能，丰富了逆变器的使用功能，适用性更广泛；并且该方法基于电流直接控制，电流响应速度快，进一步保证了系统的响应速度，提高了工作效率。The beneficial effects of the present invention are: on the basis of the general-purpose single-phase current-mode five-level inverter circuit topology, the present invention can reduce the current sharing inductance value from mH level to uH level through high-frequency modulation, effectively improving the current-mode multi-level. Practicality of level converters. The invention uses the single-phase current source type five-level converter based on the uH level current sharing inductance for the grid-connected inverter, and like the traditional voltage type inverter, the harmonic self-resonance problem on the output side will also occur. The invention not only solves the harmonic self-resonance problem in the pure active grid-connected mode (power factor is 1) by using the high-frequency harmonic current compensation method, but also provides two modes of pure reactive power and active power + reactive power. Therefore, the effect of adjustable power factor can be realized when connecting to the grid. Therefore, in addition to being used for conventional grid-connected power generation, the single-phase current source five-level converter and its harmonic suppression strategy proposed in the present invention also have a reactive power compensation function, which enriches the use function of the inverter, and is suitable for And the method is based on direct current control, and the current response speed is fast, which further ensures the response speed of the system and improves the work efficiency.

作为优选，在步骤S4中，经过处理得到电容电压uc的基波分量ucb的具体方法为：采样电容电压uc，对电容电压uc依次进行αβ-dq变换和dq-αβ变换处理，获得dq坐标系下的直流电流ucd和ucq，再将直流电流ucd和ucq分别经过电容反馈电压的低通滤波处理电路中的低通滤波器处理，处理后分别得到ucd和ucq的基波分量ucdb和ucqb，再经dq-αβ反变换后得到电容电压uc的基波分量ucb。Preferably, in step S4, the specific method for obtaining the fundamental wave component ucb of the capacitor voltage uc after processing is as follows: sampling the capacitor voltage uc , and sequentially performing αβ -dq transformation and dq-αβ transformation on the capacitor voltage uc, The DC currents u cd and u cq in the dq coordinate system are obtained, and then the DC currents u cd and u cq are respectively processed by the low-pass filter in the low-pass filter processing circuit of the capacitor feedback voltage, and u cd and u are obtained after processing. The fundamental components of cq , u cdb and u cqb , are inversely transformed by dq-αβ to obtain the fundamental component u cb of the capacitor voltage uc .

作为优选，所述高频谐波分量等于电容电压uc与基波分量ucb之差。Preferably, the high frequency harmonic component is equal to the difference between the capacitor voltage uc and the fundamental wave component ucb .

附图说明Description of drawings

图1为本发明一种基于单相电流源型五电平逆变器的并网谐波抑制方法的原理图；1 is a schematic diagram of a grid-connected harmonic suppression method based on a single-phase current source five-level inverter of the present invention;

图2为本发明中当设定Id *＝15、Iq *＝0时的并网电流波形图；FIG. 2 is a waveform diagram of grid-connected current when I d * = 15 and I q * = 0 are set in the present invention;

图3为本发明中当设定Id *＝0、Iq *＝-19时的并网电流波形图；Fig. 3 is the waveform diagram of grid-connected current when I d * = 0 and I q * = -19 are set in the present invention;

图4为本发明中当Id *＝15、Iq *＝-15时的并网电流波形图；Fig. 4 is the waveform diagram of grid-connected current when I d * =15, I q * =-15 in the present invention;

如图所示：1、单相电流型五电平逆变电路；2、CLL滤波电路；3、网侧电源电路；4、锁相环电路；5、单相交流电流的坐标变换电路；6、基于PI的直接电流控制电路；7、电容反馈电压的低通滤波处理电路；8、高频谐波电流补偿电路；9、并网电流参考信号电路；10、多载波PWM发生器驱动电路。As shown in the figure: 1. Single-phase current type five-level inverter circuit; 2. CLL filter circuit; 3. Grid-side power supply circuit; 4. Phase-locked loop circuit; 5. Coordinate transformation circuit of single-phase AC current; 6. , PI-based direct current control circuit; 7. Low-pass filter processing circuit of capacitor feedback voltage; 8. High-frequency harmonic current compensation circuit; 9. Grid-connected current reference signal circuit; 10. Multi-carrier PWM generator drive circuit.

具体实施方式Detailed ways

以下参照附图并结合具体实施方式来进一步描述发明，以令本领域技术人员参照说明书文字能够据以实施，本发明保护范围并不受限于该具体实施方式。The invention is further described below with reference to the accompanying drawings and in conjunction with specific embodiments, so that those skilled in the art can implement it with reference to the description, and the protection scope of the present invention is not limited to the specific embodiments.

本发明涉及一种基于单相电流源型五电平逆变器的并网谐波抑制方法，该方法通过基于小均流电感单相电流型五电平逆变器的并网系统实施，所述基于小均流电感单相电流型五电平逆变器的并网系统包括主电路部分以及控制电路部分，如图1所示，所述主电路部分包括单相电流型五电平逆变电路1、由滤波电容和引线等效电感构成的CLL滤波电路2以及网侧电源电路3，所述控制电路部分包括锁相环电路4、单相交流电流的坐标变换电路5、基于PI的直接电流控制电路6、电容反馈电压的低通滤波处理电路7、高频谐波电流补偿电路8、并网电流参考信号电路9以及多载波PWM发生器驱动电路10，所述基于PI的直接电流控制电路6包括一级PI调节器，该方法包括下列步骤：The invention relates to a grid-connected harmonic suppression method based on a single-phase current source type five-level inverter. The grid-connected system based on a single-phase current-type five-level inverter with a small current-sharing inductance includes a main circuit part and a control circuit part. As shown in Figure 1, the main circuit part includes a single-phase current-type five-level inverter. Circuit 1, CLL filter circuit 2 composed of filter capacitor and lead equivalent inductance, and grid-side power supply circuit 3, the control circuit part includes a phase-locked loop circuit 4, a coordinate transformation circuit 5 for single-phase AC current, and a PI-based direct Current control circuit 6, low-pass filter processing circuit 7 of capacitor feedback voltage, high-frequency harmonic current compensation circuit 8, grid-connected current reference signal circuit 9 and multi-carrier PWM generator drive circuit 10, the PI-based direct current control Circuit 6 includes a one-stage PI regulator, and the method includes the following steps:

S1、如图1所示，采集电网电压us作为参考信号，电网电压us通过锁相环电路4进行锁相处理后得到参考相位角θ，将参考相位角θ分别送入单相交流电流的坐标变换电路5和基于PI的直接电流控制电路6，分别用于αβ-dq变换和dq-αβ变换；S1. As shown in Figure 1, the grid voltage u s is collected as a reference signal, the grid voltage u s is phase-locked by the phase-locked loop circuit 4 to obtain the reference phase angle θ, and the reference phase angle θ is respectively sent into the single-phase AC current The coordinate transformation circuit 5 and the PI-based direct current control circuit 6 are respectively used for αβ-dq transformation and dq-αβ transformation;

S2、采集电网电流is，电网电流is通过单相交流电流的坐标变换电路5进行αβ-dq变换处理，获得dq坐标系下的直流电流Id和Iq，并将直流电流Id和Iq送入基于PI的直接电流控制电路6作为PI调节器的负反馈信号；S2. Collect the grid current is, and the grid current is is subjected to αβ -dq transformation processing through the coordinate transformation circuit 5 of the single-phase AC current to obtain the DC currents I d and I q in the dq coordinate system, and convert the DC currents I d and I d to I q is sent into the PI-based direct current control circuit 6 as the negative feedback signal of the PI regulator;

S3、设定理论值Id *和Iq *，Id *表示需向电网注入的有功电流值，Iq *表示需向电网注入的无功电流值，将Id *和Iq *输入基于PI的直接电流控制电路6中，分别与负反馈信号Id和Iq进行比较，比较后获得各自的电流误差信号，将电流误差信号经PI调节器后得到新的d-q轴直流电流Isd和Isq，再经dq-αβ反变换后得到单相交流电流isa；S3. Set the theoretical values I d * and I q * , I d * represents the active current value to be injected into the grid, I q * represents the reactive current value to be injected into the grid, input I d * and I q * In the PI-based direct current control circuit 6, the negative feedback signals I d and I q are compared respectively, and the respective current error signals are obtained after the comparison, and the new dq-axis DC current I sd is obtained by passing the current error signal through the PI regulator and I sq , the single-phase alternating current isa is obtained after inverse dq- αβ transformation;

S4、采样电容电压uc，经过处理得到电容电压uc的基波分量ucb；S4, sampling the capacitor voltage uc, and obtaining the fundamental wave component ucb of the capacitor voltage uc after processing ;

S5、通过高频谐波电流补偿电路中有功电流和无功电流的给定值来判断并网模式，并根据并网模式来选择需要构建的谐波反馈电流iRC；uc和ucb用于构建谐波反馈电流，Id *和Iq *用于判别并网的工作模式(纯有功模式或无功模式)，具体过程为：当Id *≠0、Iq *＝0时，即以纯有功模式并网，选择电容电压uc作为反馈电流iRC；当Id *＝0、Iq *≠0时，即以纯无功模式并网，选择电容电压uc的高频谐波分量作为反馈电流iRC，所述高频谐波分量为电容电压uc与基波分量ucb之差；当Id *≠0、Iq *≠0时，即以有功+无功模式并网，选择电容电压uc的高频谐波分量作为反馈电流iRC，所述高频谐波分量为电容电压uc与基波分量ucb之差。S5. Judge the grid-connected mode by the given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and select the harmonic feedback current i RC to be constructed according to the grid-connected mode; uc and u cb use In order to construct the harmonic feedback current, I d * and I q * are used to judge the grid-connected working mode (pure active power mode or reactive power mode). The specific process is: when I d * ≠0, I q * =0, That is, it is connected to the grid in pure active mode, and the capacitor voltage uc is selected as the feedback current i RC ; when I d * = 0, I q * ≠ 0, it is connected to the grid in pure reactive mode, and the high-frequency harmonic of the capacitor voltage u c is selected . The component is the feedback current i RC , and the high-frequency harmonic component is the difference between the capacitor voltage uc and the fundamental wave component u cb ; when I d * ≠ 0, I q * ≠0, that is, in the active + reactive mode network, the high-frequency harmonic component of the capacitor voltage uc is selected as the feedback current i RC , and the high-frequency harmonic component is the difference between the capacitor voltage uc and the fundamental component ucb .

S6、在获得单相交流电流isa的基础上，通过往基于PI的直接电流控制电路6中反向注入谐波补偿电流iRC与单相交流电流isa进行比较，比较后获得新的交流电流is ’，经幅值标幺化处理后得到正弦调制信号is *，即并网电流参考信号；S6. On the basis of obtaining the single-phase AC current isa , compare the harmonic compensation current i RC with the single-phase AC current isa by reversely injecting the harmonic compensation current i RC into the direct current control circuit 6 based on PI, and obtain a new AC current after the comparison. The current is ' , the sinusoidal modulation signal is * is obtained after the amplitude per- unitization process, that is, the grid-connected current reference signal;

S7、将得到的正弦调制信号is *送入多载波PWM发生器驱动电路10中，通过多载波PWM发生器产生八路SPWM信号，经隔离驱动后控制单相电流型五电平逆变电路1中的各个开关器件的开通与关断。S7, send the obtained sinusoidal modulation signal is * into the multi-carrier PWM generator drive circuit 10, generate eight-way SPWM signals through the multi-carrier PWM generator, and control the single-phase current type five-level inverter circuit 1 after isolation and driving The turn-on and turn-off of each switching device.

本发明在通用型单相电流型五电平逆变电路拓扑基础上，通过高频调制可将均流电感值从mH级减少到uH级，有效提升了电流型多电平变流器的实用性。本发明将基于uH级均流电感的单相电流源型五电平变流器用于并网逆变，与传统电压型逆变器一样也会产生输出侧的谐波自谐振问题。本发明通过采用高频谐波电流补偿的方法不仅解决了纯有功并网模式(功率因数为1)时的谐波自谐振问题，而且还提供了纯无功以及有功+无功这两种模式下的谐振抑制方法，从而实现了并网时任意功率因数可调的效果，具体效果参见图2、图3和图4所示的并网电流波形。因此，本发明所提的单相电流源型五电平变流器及其谐波抑制策略除了用于常规的并网发电，还具有无功补偿功能，丰富了逆变器的使用功能，适用性更广泛；并且该方法基于电流直接控制，电流响应速度快，进一步保证了系统的响应速度，提高了工作效率。Based on the general-purpose single-phase current-type five-level inverter circuit topology, the invention can reduce the current sharing inductance value from mH level to uH level through high-frequency modulation, thereby effectively improving the practicality of the current-type multilevel converter. sex. The invention uses the single-phase current source type five-level converter based on the uH level current sharing inductance for the grid-connected inverter, and like the traditional voltage type inverter, the harmonic self-resonance problem on the output side will also occur. The invention not only solves the harmonic self-resonance problem in the pure active grid-connected mode (power factor is 1) by using the high-frequency harmonic current compensation method, but also provides two modes of pure reactive power and active power + reactive power. Therefore, the effect of adjustable power factor can be achieved when the grid is connected. For the specific effect, see the grid-connected current waveforms shown in Figure 2, Figure 3 and Figure 4. Therefore, in addition to being used for conventional grid-connected power generation, the single-phase current source five-level converter and its harmonic suppression strategy proposed in the present invention also have a reactive power compensation function, which enriches the use function of the inverter, and is suitable for And the method is based on direct current control, and the current response speed is fast, which further ensures the response speed of the system and improves the work efficiency.

在步骤S4中，经过处理得到电容电压uc的基波分量ucb的具体方法为：采样电容电压uc，对电容电压uc依次进行αβ-dq变换和dq-αβ变换处理，获得dq坐标系下的直流电流ucd和ucq，再将直流电流ucd和ucq分别经过电容反馈电压的低通滤波处理电路7中的低通滤波器处理，处理后分别得到ucd和ucq的基波分量ucdb和ucqb，再经dq-αβ反变换后得到电容电压uc的基波分量ucb。In step S4, the specific method for obtaining the fundamental wave component ucb of the capacitor voltage uc after processing is as follows: sampling the capacitor voltage uc , and sequentially performing αβ -dq transformation and dq-αβ transformation on the capacitor voltage uc to obtain dq coordinates The DC currents u cd and u cq under the system are respectively processed by the low-pass filter in the low-pass filter processing circuit 7 of the capacitor feedback voltage, and the values of u cd and u cq are obtained after processing . The fundamental wave components ucdb and u cqb are inversely transformed by dq-αβ to obtain the fundamental wave component ucb of the capacitor voltage uc .

本发明分别针对三种并网工作模式进行了仿真验证，(1)纯有功模式：设定Id *＝15、Iq *＝0；(2)纯无功模式：设定Id *＝0、Iq *＝-19；(3)有功+无功模式：设定Id *＝15、Iq *＝-15。为了便于对比控制效果，设定t＝0.1s时，用于补偿的反馈电流信号才投入控制。如图2、图3和图4所示，可以看出：三种并网工作模式下，单相电流型五电平逆变电路1输出侧的谐波自谐振问题均能很好地得到抑制，入网电流波形接近于正弦波，同时可实现并网时任意功率因数可调。The present invention has carried out simulation verification for three grid-connected working modes respectively, (1) pure active mode: set I d * = 15, I q * = 0; (2) pure reactive power mode: set I d * = 0. I q * = -19; (3) Active + reactive mode: set I d * = 15, I q * = -15. In order to facilitate the comparison of control effects, the feedback current signal used for compensation is only put into control when t=0.1s is set. As shown in Figure 2, Figure 3 and Figure 4, it can be seen that under the three grid-connected operating modes, the harmonic self-resonance problem at the output side of the single-phase current-type five-level inverter circuit 1 can be well suppressed , the grid current waveform is close to a sine wave, and at the same time, any power factor can be adjusted when the grid is connected.

本发明在通用的电路拓扑基础上，通过高频调制将均流电感值从mH级减少到uH级，进一步提升电流型多电平变流器的实用性。在此基础上，本发明基于小均流电感单相电流型五电平逆变器，提出一种电流谐波补偿方法以解决逆变器输出侧的谐波自谐振问题，通过采样滤波电容C上的电压，分别经αβ-dq变换、低通滤波以及dq-αβ反变换处理后获得50Hz电压基波分量，与原始电容电压相减即可获得高频谐波分量，利用该高频谐波分量对并网电流进行谐波补偿。在纯有功、纯无功以及有功+无功三种不同并网工作模式下，该补偿方法均能起到抑制谐振的效果，具体效果参见图2、图3和图4所示的并网电流波形。On the basis of general circuit topology, the present invention reduces the current sharing inductance value from mH level to uH level through high frequency modulation, and further improves the practicability of the current mode multilevel converter. On this basis, the present invention proposes a current harmonic compensation method based on a small current-sharing inductance single-phase current-type five-level inverter to solve the harmonic self-resonance problem at the output side of the inverter. By sampling the filter capacitor C After αβ-dq transformation, low-pass filtering and dq- αβ inverse transformation processing, the fundamental voltage of 50Hz voltage can be obtained, and the high-frequency harmonic component can be obtained by subtracting it from the original capacitor voltage. The wave component performs harmonic compensation on the grid-connected current. In the three different grid-connected working modes of pure active power, pure reactive power and active power + reactive power, this compensation method can suppress resonance. waveform.

Claims (3)

1. A grid-connected harmonic suppression method based on a single-phase current source type five-level inverter is characterized by comprising the following steps: the method is implemented by a grid-connected system based on a small current-sharing inductance single-phase current type five-level inverter, the grid-connected system based on the small current-sharing inductance single-phase current type five-level inverter comprises a main circuit part and a control circuit part, the main circuit part comprises a single-phase current type five-level inverter circuit (1), a CLL filter circuit (2) and a grid-side power circuit (3), the control circuit part comprises a phase-locked loop circuit (4), a single-phase alternating current coordinate transformation circuit (5), a PI-based direct current control circuit (6), a low-pass filter processing circuit (7) of capacitance feedback voltage, a high-frequency harmonic current compensation circuit (8), a grid-connected current reference signal circuit (9) and a multi-carrier PWM generator driving circuit (10), the PI-based direct current control circuit (6) comprises a first-stage PI regulator, the method comprises the following steps:
s1, collecting the voltage u of the power grid s As reference signal, the grid voltage u s The phase-locked loop circuit (4) is used for performing phase-locked processing to obtain a reference phase angle theta, and the reference phase angle theta is respectively sent to a coordinate conversion circuit (5) of single-phase alternating current and a direct current control circuit (6) based on PI and is respectively used for alpha beta-dq conversion and dq-alpha beta conversion;
s2, collecting power grid current i s Grid current i s Alpha beta-dq conversion processing is carried out through a coordinate conversion circuit (5) of the single-phase alternating current to obtain direct current I under a dq coordinate system d And I q And applying a direct current I d And I q The signal is sent to a direct current control circuit (6) based on the PI to be used as a negative feedback signal of a PI regulator;
s3, setting a theoretical value I d * And I q * ，I d * Representing the value of the active current to be injected into the grid, I q * Representing the value of the reactive current to be injected into the network, I d * And I q * Input into a PI-based direct current control circuit (6) and respectively connected with a negative feedback signal I d And I q Comparing to obtain respective current error signals, and passing the current error signals through PI regulator to obtain new d-q axis DC current I sd And I sq Then carrying out dq-alpha beta inverse transformation to obtain single-phase alternating current i sa ；
S4, sampling capacitor voltage u c Processed to obtain a capacitor voltage u c Fundamental component u of cb ；
S5, judging a grid-connected mode through given values of active current and reactive current in the high-frequency harmonic current compensation circuit, and selecting feedback current i to be constructed according to the grid-connected mode RC (ii) a The specific process is as follows: when I is d * ≠0、I q * When the voltage is equal to 0, namely the grid connection is carried out in a pure active mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I d * ＝0、I q * When not equal to 0, namely grid connection is carried out in a pure reactive mode, and the capacitor voltage u is selected c As a feedback current i RC (ii) a When I is d * ≠0、I q * When the voltage is not equal to 0, namely the grid connection is carried out in an active mode and a reactive mode, and the capacitor voltage u is selected c As a feedback current i RC ；
S6, obtaining a single-phase alternating current i sa Based on the above, by injecting a harmonic compensation current i in reverse direction into a PI-based direct current control circuit (6) RC With single-phase alternating current i sa Comparing to obtain new AC current i s ’ Obtaining a sinusoidal modulation signal i after amplitude per unit processing s * I.e. the grid-connected current reference signal;
s7, obtaining the sine modulation signal i s * The signal is sent into a multi-carrier PWM generator driving circuit (10), eight paths of SPWM signals are generated through the multi-carrier PWM generator, and the switching-on and switching-off of each switching device in the single-phase current type five-level inverter circuit (1) are controlled after isolation driving.
2. Grid-connected harmonic suppression device based on single-phase current source type five-level inverter according to claim 1The manufacturing method is characterized in that: in step S4, the processing results in the capacitor voltage u c Fundamental component u of cb The specific method comprises the following steps: sampling capacitor voltage u c To the capacitor voltage u c Carrying out alpha beta-dq conversion and dq-alpha beta conversion treatment in sequence to obtain direct current u under dq coordinate system cd And u cq Then, the DC current u is applied cd And u cq Respectively processed by a low-pass filter in a low-pass filter processing circuit (7) of the capacitor feedback voltage to respectively obtain u cd And u cq Fundamental component u of cdb And u cqb And then carrying out dq-alpha beta inverse transformation to obtain a capacitor voltage u c Fundamental component u of cb 。
3. The grid-connected harmonic suppression method based on the single-phase current source type five-level inverter according to claim 1, characterized in that: the high-frequency harmonic component is equal to the capacitor voltage u c And the fundamental component u cb The difference between them.
CN202111542621.9A 2021-12-16 2021-12-16 Grid-connected harmonic suppression method based on single-phase current source type five-level inverter Pending CN114915195A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115642599A (en) * 2022-12-26 2023-01-24 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN116961018A (en) * 2023-09-18 2023-10-27 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115642599A (en) * 2022-12-26 2023-01-24 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN115642599B (en) * 2022-12-26 2023-03-31 浙江日风电气股份有限公司 Harmonic current suppression method, control device and power generation system
CN116961018A (en) * 2023-09-18 2023-10-27 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof
CN116961018B (en) * 2023-09-18 2023-12-12 锦浪科技股份有限公司 Flyback micro inverter system and working method thereof

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