CN104659813B

CN104659813B - A kind of multi-inverter parallel control method of quick harmonic circulating current suppression

Info

Publication number: CN104659813B
Application number: CN201510057802.0A
Authority: CN
Inventors: 罗安; 周小平; 陈燕东; 周乐明; 李鸣慎; 匡慧敏; 伍文华; 杨苓; 怀坤山
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2015-02-04
Filing date: 2015-02-04
Publication date: 2016-08-17
Anticipated expiration: 2035-02-04
Also published as: CN104659813A

Abstract

The invention discloses a multi-inverter parallel control method for rapid harmonic circulation suppression. The harmonic current of the output current of the inverter is obtained through the i _p -i _q algorithm, and the phase is inverted and then superimposed on the voltage outer loop output , to obtain the command of the current inner loop, thereby efficiently and quickly suppressing the harmonic circulating current of the inverter output current, and realizing the harmonic circulating current suppression of multiple inverters connected in parallel. The present invention also proposes a calculation method of "variable window" sliding average power to improve the calculation of average power, reduce the deviation introduced by traditional fixed-period calculation, and improve the accuracy of average power calculation; the proposal of sliding average calculation, The average power can be calculated once in each sampling period, thereby greatly improving the real-time performance of power calculation, enabling power droop control to better realize power sharing and further reduce harmonic circulation. The invention can be widely used in the parallel control system of multi-inverters in the micro-grid, and is especially suitable for the micro-grid operating with non-linear loads.

Description

A Multi-inverter Parallel Control Method for Fast Harmonic Circulating Current Suppression

技术领域technical field

本发明涉及微电网多逆变器并联控制技术领域，特别是一种快速谐波环流抑制的多逆变器并联控制方法。The invention relates to the technical field of multi-inverter parallel control of a microgrid, in particular to a multi-inverter parallel control method for fast harmonic circulation suppression.

背景技术Background technique

随着全球能源危机和环境污染问题的日益严峻，人们越来越重视新能源的开发与利用，新能源作为一种分布广泛的高效清洁能源，对传统能源的替代比率将越来越大。目前，新能源发电被认为是世界上最具发展前景的新能源技术，各国家纷纷投入巨额资金进行开发研究，并大力拓展其市场应用。微电网作为新能源的开发与利用的一种有效手段，可以对分布式电源进行高效地利用。With the increasingly severe global energy crisis and environmental pollution, people pay more and more attention to the development and utilization of new energy. As a widely distributed and efficient clean energy, new energy will replace traditional energy more and more. At present, new energy power generation is considered to be the most promising new energy technology in the world, and countries have invested huge sums of money in research and development, and vigorously expand its market application. As an effective means for the development and utilization of new energy, microgrid can efficiently utilize distributed power.

微电网运行的一个关键问题是多逆变器的并联运行，而在并联运行时由于控制不当或者线路阻抗不一致，会在逆变器之间产生环流，尤其是带非线性负荷时，逆变器之间谐波环流会很大。目前，一般采用虚拟阻抗的方法来减小环流，对基波环流抑制效果比较好，但是很难实现对谐波环流的抑制，甚至会增加逆变器输出电压的畸变率。因此研究一种快速谐波环流抑制的多逆变器并联控制方法意义重大。A key issue in the operation of the microgrid is the parallel operation of multiple inverters. During parallel operation, due to improper control or inconsistent line impedance, a circulating current will be generated between the inverters, especially when there is a nonlinear load. The harmonic circulation between them will be very large. At present, the method of virtual impedance is generally used to reduce the circulating current, and the effect of suppressing the fundamental circulating current is better, but it is difficult to suppress the harmonic circulating current, and it will even increase the distortion rate of the inverter output voltage. Therefore, it is of great significance to study a multi-inverter parallel control method for fast harmonic circulating current suppression.

发明内容Contents of the invention

本发明所要解决的技术问题是，针对现有技术不足，提供一种快速谐波环流抑制的多逆变器并联控制方法。The technical problem to be solved by the present invention is to provide a multi-inverter parallel control method for rapid harmonic circulation suppression in view of the deficiencies of the prior art.

为解决上述技术问题，本发明所采用的技术方案是：一种快速谐波环流抑制的多逆变器并联控制方法，适用于微电网多逆变器并联系统；所述微电网多逆变器并联系统包括多个并联的三相逆变系统；所述三相逆变系统包括依次连接的直流储能电容、三相逆变桥、LCL滤波电路；所述三相逆变系统通过线路阻抗接入微电网交流母线；包括以下步骤：In order to solve the above technical problems, the technical solution adopted in the present invention is: a multi-inverter parallel control method for rapid harmonic circulation suppression, which is suitable for a micro-grid multi-inverter parallel system; the micro-grid multi-inverter The parallel system includes a plurality of parallel three-phase inverter systems; the three-phase inverter system includes DC energy storage capacitors, three-phase inverter bridges, and LCL filter circuits connected in sequence; the three-phase inverter system is connected through line impedance into the AC bus of the microgrid; including the following steps:

1)在每个采样周期的起始点，采样电路对逆变器输出电压u_a、u_b、u_c，输出电流i_a、i_b、i_c进行采样，然后通过控制器对采样得到的数据进行读取、存储；1) At the beginning of each sampling period, the sampling circuit samples the inverter output voltages u _a , _{ub , uc , output currents ia , i b , i c} _, _and _then _the controller samples the sampled data Read and store;

2)控制器将第1步采集得到的逆变器输出电压u_a实时地传送至数字锁相环(PLL模块)，计算得到当前相位角频率ω_o和频率f；2) The controller transmits the inverter output voltage u _a collected in the first step to the digital phase-locked loop (PLL module) in real time, and calculates the current phase angular frequency ω _o and frequency f;

3)将第1步采集得到的输出电流i_a、i_b、i_c从abc坐标系变换到αβ坐标系下，得到i_α、i_β，其计算公式为：3) Transform the output currents i _a , i _b , and i _c acquired in the first step from the abc coordinate system to the αβ coordinate system to obtain i _α , i _β , and their calculation formulas are:

$[\begin{matrix} {i i}_{α α} \\ {i i}_{β β} \end{matrix}] = = {C C}_{abc abc / / αβ αβ} [\begin{matrix} {i i}_{a a} \\ {i i}_{b b} \\ {i i}_{c c} \end{matrix}] = = \sqrt{\frac{22}{33}} [\begin{matrix} 11 & - - \frac{11}{22} & - - \frac{11}{22} \\ 00 & \frac{\sqrt{33}}{22} & - - \frac{\sqrt{33}}{22} \end{matrix}] [\begin{matrix} {i i}_{a a} \\ {i i}_{b b} \\ {i i}_{c c} \end{matrix}]$

4)将αβ坐标系下的电流i_α、i_β变换到旋转dq坐标系下，得到旋转坐标系下的电流i_p、i_q，其计算公式如下：4) Transform the currents i _α and i _β in the αβ coordinate system to the rotating dq coordinate system to obtain the currents i _p and i _q in the rotating coordinate system. The calculation formula is as follows:

$[\begin{matrix} {i i}_{p p} \\ {i i}_{q q} \end{matrix}] = = {C C}_{αβ αβ / / dq dq} [\begin{matrix} {i i}_{α α} \\ {i i}_{β β} \end{matrix}] = = [\begin{matrix} sin sin {ω ω}_{o o} t t & - - cos cos {ω ω}_{o o} t t \\ - - cos cos {ω ω}_{o o} t t & - - sin sin {ω ω}_{o o} t t \end{matrix}] [\begin{matrix} {i i}_{α α} \\ {i i}_{β β} \end{matrix}]$

5)电流i_p、i_q可以分解为直流分量和交流分量将电流i_p、i_q通过低通滤波器LPF后，得到直流分量 5) Current i _p and i _q can be decomposed into DC components and AC components After passing the current i _p and i _q through the low-pass filter LPF, the DC component is obtained

6)将直流分量变换到αβ坐标系下，得到αβ坐标系下的直流分量电流其计算公式如下：6) The DC component Transform to the αβ coordinate system to obtain the DC component current in the αβ coordinate system Its calculation formula is as follows:

$[\begin{matrix} \overset{&OverBar; &OverBar;}{{i i}_{α α}} \\ \overset{&OverBar; &OverBar;}{{i i}_{β β}} \end{matrix}] = = {C C}_{dq dq / / αβ αβ} [\begin{matrix} \overset{&OverBar; &OverBar;}{{i i}_{p p}} \\ \overset{&OverBar; &OverBar;}{{i i}_{q q}} \end{matrix}] = = [\begin{matrix} sin sin {ω ω}_{o o} t t & - - cos cos {ω ω}_{o o} t t \\ - - cos cos {ω ω}_{o o} t t & - - sin sin {ω ω}_{o o} t t \end{matrix}] [\begin{matrix} \overset{&OverBar; &OverBar;}{{i i}_{p p}} \\ \overset{&OverBar; &OverBar;}{{i i}_{q q}} \end{matrix}]$

7)再用电流i_α、i_β变减去直流分量电流得到αβ坐标系下的交流分量其计算公式如下：7) Then use the current i _α and i _β to subtract the DC component current Get the AC component in the αβ coordinate system Its calculation formula is as follows:

$\{\begin{matrix} \overset{~ ~}{{i i}_{α α}} = = {i i}_{α α} - - \overset{&OverBar; &OverBar;}{{i i}_{α α}} \\ \overset{~ ~}{{i i}_{β β}} = = {i i}_{β β} - - \overset{&OverBar; &OverBar;}{{i i}_{β β}} \end{matrix}$

8)将第1步采集得到的逆变器输出电压u_a、u_b、u_c从abc坐标系变换到αβ坐标系下，得到u_α、u_β，其计算公式为：8) Transform the inverter output voltages u _a , u _b , u _c collected in the first step from the abc coordinate system to the αβ coordinate system to obtain u _α , u _β , and their calculation formulas are:

$[\begin{matrix} {u u}_{α α} \\ {u u}_{β β} \end{matrix}] = = {C C}_{abc abc / / αβ αβ} [\begin{matrix} {u u}_{a a} \\ {u u}_{b b} \\ {u u}_{c c} \end{matrix}] = = \sqrt{\frac{22}{33}} [\begin{matrix} 11 & - - \frac{11}{22} & - - \frac{11}{22} \\ 00 & \frac{\sqrt{33}}{22} & - - \frac{\sqrt{33}}{22} \end{matrix}] [\begin{matrix} {u u}_{a a} \\ {u u}_{b b} \\ {u u}_{c c} \end{matrix}]$

9)利用第3步得到的输出电流i_α、i_β和第8步得到的输出电压u_α、u_β，计算瞬时有功功率p和无功功率q，其计算公式如下：9) Use the output current i _α , i _β obtained in step 3 and the output voltage u _α , u _β obtained in step 8 to calculate the instantaneous active power p and reactive power q, and the calculation formula is as follows:

$[\begin{matrix} p p \\ q q \end{matrix}] = = [\begin{matrix} {u u}_{α α} & {u u}_{β β} \\ {u u}_{β β} & - - {u u}_{α α} \end{matrix}] [\begin{matrix} {i i}_{α α} \\ {i i}_{β β} \end{matrix}]$

10)将计算得到的瞬时有功功率p和无功功率q送入变窗口滑动平均功率计算模块，计算得到平均有功功率P和无功功率Q，并将当前计算得到的平均有功功率P和无功功率Q进行存储，以备下次计算使用。其计算公式如下：10) Send the calculated instantaneous active power p and reactive power q to the variable window sliding average power calculation module, calculate the average active power P and reactive power Q, and transfer the current calculated average active power P and reactive power The power Q is stored for use in the next calculation. Its calculation formula is as follows:

$\{\begin{matrix} P P ((k k)) = = P P ((k k - - 11)) + + \frac{11}{N N} ((p p ((k k)) - - p p ((k k - - N N)))) \\ Q Q ((k k)) = = Q Q ((k k - - 11)) + + \frac{11}{N N} ((q q ((k k)) - - q q ((k k - - N N)))) \end{matrix}$

其中k为当前采样次数，N为一个电网周期里的总采样点数，且与输入频率成正比；Where k is the current number of sampling times, N is the total number of sampling points in a grid cycle, and is proportional to the input frequency;

11)利用计算得到的平均有功功率P和无功功率Q，通过功率下垂控制计算得到参考电压幅值E和角频率ω，具体计算公式如下：11) Use the calculated average active power P and reactive power Q to calculate the reference voltage amplitude E and angular frequency ω through power droop control. The specific calculation formula is as follows:

$\{\begin{matrix} E E. = = {E E.}^{* *} - - mQ mQ \\ ω ω = = {ω ω}^{* *} - - nP nP \end{matrix}$

其中m、n分别为有功和无功的下垂系数，具体取值由三相逆变系统的有功容量和无功容量决定；Among them, m and n are the droop coefficients of active power and reactive power respectively, and the specific values are determined by the active capacity and reactive capacity of the three-phase inverter system;

12)利用第11步计算得到的参考电压幅值E和角频率ω与第2步得到的相位进行三相电压合成得到三相参考电压其计算公式如下：12) Use the reference voltage amplitude E and angular frequency ω calculated in step 11 and the phase obtained in step 2 Perform three-phase voltage synthesis to obtain a three-phase reference voltage Its calculation formula is as follows:

13)将合成得到的三相参考电压变换到αβ坐标系下，得到αβ坐标系下的参考电压其计算公式为：13) The synthesized three-phase reference voltage Transform to the αβ coordinate system to obtain the reference voltage in the αβ coordinate system Its calculation formula is:

$[\begin{matrix} {u u}_{α α}^{* *} \\ {u u}_{β β}^{* *} \end{matrix}] = = {C C}_{abc abc / / αβ αβ} [\begin{matrix} {u u}_{a a}^{* *} \\ {u u}_{b b}^{* *} \\ {u u}_{c c}^{* *} \end{matrix}] = = \sqrt{\frac{22}{33}} [\begin{matrix} 11 & - - \frac{11}{22} & - - \frac{11}{22} \\ 00 & \frac{\sqrt{33}}{22} & - - \frac{\sqrt{33}}{22} \end{matrix}] [\begin{matrix} {u u}_{a a}^{* *} \\ {u u}_{b b}^{* *} \\ {u u}_{c c}^{* *} \end{matrix}]$

14)将第3步得到的i_α、i_β，乘以虚拟电阻，再叠加到参考电压上，得到准谐振PR控制电压外环的电压参考值通过准谐振PR控制之后得到电流内环的参考电流 14) Multiply the i _α and i _β obtained in step 3 by the virtual resistance, and then superimpose it to the reference voltage On, the voltage reference value of the quasi-resonant PR control voltage outer loop is obtained After quasi-resonant PR control, the reference current of the current inner loop is obtained

15)将第7步得到的αβ坐标系下的交流分量相位取反，叠加到电流内环的参考电流上，得到参考电流 15) The AC component in the αβ coordinate system obtained in step 7 The phase is reversed and superimposed to the reference current of the current inner loop on, get the reference current

16)将参考电流变换到abc坐标系下，得到电流无差拍控制的参考电流经过无差拍控制得到三相逆变桥驱动信号的占空比D_a、D_b、D_c。将其传送至驱动保护电路，产生驱动信号，用来驱动逆变器。16) Set the reference current Transform to the abc coordinate system to obtain the reference current for current deadbeat control The duty ratios D _a , D _b , and D _c of the three-phase inverter bridge drive signals are obtained through deadbeat control. Send it to the drive protection circuit to generate a drive signal to drive the inverter.

与现有技术相比，本发明所具有的有益效果为：本发明提出的快速谐波环流抑制的多逆变器并联控制方法将逆变器输出电流的谐波电流反相后叠加到电压外环输出，得到电流内环的指令，从而高效、快速地抑制了谐波环流。此外，本发明提出了一种变窗口滑动平均功率的计算方法来计算功率下垂控制所需的平均功率，滑动平均计算的提出提高了功率计算的实时性，使得在每个采样周期里都能计算一次平均功率；“变窗口”的提出减少了定周期计算引入的误差，提高了平均功率计算的准确性，从而实现了多逆变器并联的功率均分，进一步降低了谐波环流。本发明实现了微电网多逆变器并联的谐波环流抑制，可广泛应用到微电网控制系统中。Compared with the prior art, the beneficial effects of the present invention are: the multi-inverter parallel control method for rapid harmonic circulation suppression proposed by the present invention reverses the harmonic current of the inverter output current and superimposes it on the external voltage Loop output, get the command of the current inner loop, thus efficiently and quickly suppress the harmonic circulation. In addition, the present invention proposes a variable window sliding average power calculation method to calculate the average power required for power droop control. The proposed sliding average calculation improves the real-time performance of power calculation, making it possible to calculate in each sampling period One-time average power; the proposal of "variable window" reduces the error introduced by fixed-period calculation and improves the accuracy of average power calculation, thereby realizing the power sharing of multiple inverters connected in parallel and further reducing harmonic circulation. The invention realizes the suppression of the harmonic circulation current of multiple inverters connected in parallel in the micro-grid, and can be widely applied to the control system of the micro-grid.

附图说明Description of drawings

图1为本发明一实施例多逆变器并联结构示意图；FIG. 1 is a schematic diagram of a parallel structure of multiple inverters according to an embodiment of the present invention;

图2为本发明一实施例快速谐波环流抑制的多逆变器并联控制方法示意图；Fig. 2 is a schematic diagram of a multi-inverter parallel control method for fast harmonic circulation suppression according to an embodiment of the present invention;

图3为本发明一实施例单相锁相环计算框图；Fig. 3 is a single-phase PLL calculation block diagram of an embodiment of the present invention;

图4为本发明一实施例采用快速谐波环流抑制的多逆变器并联控制方法的两逆变器并联电流仿真波形图。FIG. 4 is a current simulation waveform diagram of parallel connection of two inverters in a multi-inverter parallel control method using fast harmonic circulation suppression according to an embodiment of the present invention.

图5(a)为传统的下垂控制方法的两逆变器并联环流谐波分析结果图；图5(b)为采用本发明方法的环流谐波分析结果图。Fig. 5(a) is a diagram of the analysis results of the circulating current harmonics of two inverters connected in parallel in the traditional droop control method; Fig. 5(b) is a diagram of the analysis results of the circulating current harmonics using the method of the present invention.

具体实施方式detailed description

图1为本发明一实施例多逆变器并联结构示意图，包括三相逆变系统、控制系统、线路阻抗、微电网交流母线、三相负载；所述三相逆变系统包括直流储能电容、三相逆变桥、LCL滤波电路；直流储能电容、三相逆变桥、LCL滤波电路、线路阻抗、微电网交流母线、三相负载依次连接。控制系统包括DSP控制器、A/D采样电路、锁相环模块和驱动保护电路。Figure 1 is a schematic diagram of a multi-inverter parallel structure according to an embodiment of the present invention, including a three-phase inverter system, a control system, line impedance, a microgrid AC bus, and a three-phase load; the three-phase inverter system includes a DC energy storage capacitor , three-phase inverter bridge, LCL filter circuit; DC energy storage capacitor, three-phase inverter bridge, LCL filter circuit, line impedance, microgrid AC bus, and three-phase load are connected in sequence. The control system includes DSP controller, A/D sampling circuit, phase-locked loop module and drive protection circuit.

图2为本发明一实施例快速谐波环流抑制的多逆变器并联控制方法示意图，主要由谐波环流抑制部分、变窗口滑动平均功率计算模块、锁相环模块、功率下垂控制模块、虚拟电阻模块、准谐振PR控制模块和电流无差拍控制模块组成，具体的快速谐波环流抑制的多逆变器并联控制方法包括以下步骤：Fig. 2 is a schematic diagram of a multi-inverter parallel control method for fast harmonic circulation suppression according to an embodiment of the present invention, which mainly consists of a harmonic circulation suppression part, a variable window sliding average power calculation module, a phase-locked loop module, a power droop control module, a virtual Composed of a resistance module, a quasi-resonance PR control module and a current deadbeat control module, the specific fast harmonic circulation suppression multi-inverter parallel control method includes the following steps:

其中m、n分别为有功和无功的下垂系数，具体数值由各逆变器的有功容量和无功容量决定的；Among them, m and n are the droop coefficients of active power and reactive power respectively, and the specific values are determined by the active capacity and reactive capacity of each inverter;

图3为本发明一实施例单相锁相环计算框图，图中u_a为电网电压，将电网电压u_a的相位滞后90°以构造β相虚拟正交信号u_β，从而构造出两相虚拟正交系统，获得两相正交电压u_α、u_β，再对两相正交电压u_α、u_β做αβ/dq坐标变换，得到微电网电压值d轴分量u_d和微电网电压值q轴分量u_q，将u_d的参考值设置为0，对其进行PI控制，可以得到当前电网的角频率ω，再经过积分得到当前电网的相位 Fig. 3 is a single-phase phase-locked loop calculation block diagram of an embodiment of the present invention, in which u _a is the grid voltage, and the phase of the grid voltage u _a is delayed by 90° to construct a β-phase virtual quadrature signal u _β , thereby constructing a two-phase The virtual orthogonal system obtains the two-phase orthogonal voltages u _α and u _β , and then performs αβ/dq coordinate transformation on the two-phase orthogonal voltages u _α and u _β to obtain the d-axis component u _d of the microgrid voltage value and the microgrid voltage value q-axis component u _q , set the reference value of u _d to 0, and perform PI control on it, the angular frequency ω of the current power grid can be obtained, and then the phase of the current power grid can be obtained through integration

图4为本发明一实施例采用快速谐波环流抑制的多逆变器并联控制方法的两逆变器并联电流仿真波形图。假定逆变器容量均为9kVA，逆变器1线路阻抗取值为0.2+j0.03Ω，逆变器2线路阻抗取值为0.25+j0.04Ω，载波频率设为10kHZ，负载为6.6kW的阻性负荷，i_a1、i_a2分别为流过逆变器1、2的A相电流，i_aH为逆变器之间的A相环流，定义为i_aH＝(i_a1-i_a2)/2，之前只有逆变器1单独运行，i_aH＝i_a1/2；0.5s后逆变器2并入系统，电流i_a1逐渐变为原来的一半，暂态过程结束后，i_a1与i_a2的幅值、相位基本相同，i_aH也基本趋向于零。FIG. 4 is a current simulation waveform diagram of parallel connection of two inverters in a multi-inverter parallel control method using fast harmonic circulation suppression according to an embodiment of the present invention. Assume that the inverter capacity is 9kVA, the line impedance of inverter 1 is 0.2+j0.03Ω, the line impedance of inverter 2 is 0.25+j0.04Ω, the carrier frequency is 10kHZ, and the load is 6.6kW Resistive load, i _a1 and i _a2 are the A-phase current flowing through the inverters 1 and 2 respectively, and i _aH is the A-phase circulating current between the inverters, defined as i _aH =(i _a1 -i _a2 )/ 2. Before, only inverter 1 operated alone, i _aH = i _a1 /2; after 0.5s, inverter 2 was integrated into the system, and the current i _a1 gradually became half of the original value. After the transient process, i _a1 and i The amplitude and phase of _a2 are basically the same, and i _aH also basically tends to zero.

图5为本发明一实施例采用快速谐波环流抑制的多逆变器并联控制方法和传统的下垂控制方法的两逆变器并联环流谐波分析对比图。其中图a为传统控制方法环流谐波分析结果，图b为本发明所提出的快速谐波环流抑制控制方法环流谐波分析结果，通过两图的对比，明显可以看到采用本发明所提出的快速谐波环流抑制控制方法之后，谐波环流的高频谐波含量明显减少。FIG. 5 is a comparison diagram of harmonic analysis of parallel circulating currents of two inverters using a fast harmonic circulating current suppression multi-inverter parallel control method and a traditional droop control method according to an embodiment of the present invention. Among them, figure a is the analysis result of the circulating current harmonics of the traditional control method, and figure b is the analysis result of the circulating current harmonics of the fast harmonic circulation suppression control method proposed by the present invention. Through the comparison of the two figures, it can be clearly seen that the method proposed by the present invention is adopted After the fast harmonic circulation suppression control method, the high-frequency harmonic content of the harmonic circulation current is significantly reduced.

Claims

1. the multi-inverter parallel control method of a quick harmonic circulating current suppression, it is adaptable to micro-capacitance sensor multi-inverter parallel system； Described micro-capacitance sensor multi-inverter parallel system includes the three-phase inversion system of multiple parallel connection；Described three-phase inversion system includes depending on The DC energy storage electric capacity of secondary connection, three phase inverter bridge, LCL filter circuit；Described three-phase inversion system passes through line impedance Access micro-capacitance sensor ac bus；It is characterized in that, comprise the following steps:

1) in the starting point in each sampling period, to three-phase inversion system output voltage u_a、u_b、u_c, export electric current i_a、i_b、 i_cSample；

2) by described three-phase inversion system output voltage u_aIt is sent to digital phase-locked loop, is calculated current phase placeAngular frequency_o With frequency f；By described three-phase inversion system output voltage u_a、u_b、u_cFrom abc coordinate system transformation to α β coordinate system, Obtain the voltage u under α β coordinate system_α、u_β；By three-phase inversion system output current i_a、i_b、i_cFrom abc coordinate system transformation Under α β coordinate system, obtain the electric current i under α β coordinate system_α、i_β；

3) by the electric current i under α β coordinate system_α、i_βTransform under rotation dq coordinate system, obtain the electric current i under rotating coordinate system_p、 i_q；

4) by electric current i_p、i_qAfter low pass filter, obtain DC component

5) by DC componentTransform under α β coordinate system, obtain DC component electric current

6) electric current i is used_α、i_βDeduct DC component electric currentObtain the AC compounent under α β coordinate system

7) electric current i is utilized_α、i_β, voltage u_α、u_βThe instantaneous active power p of calculating three-phase inversion system and reactive power q:

[\begin{matrix} p \\ q \end{matrix}] = [\begin{matrix} u_{α} & u_{β} \\ u_{β} & - u_{α} \end{matrix}] [\begin{matrix} i_{α} \\ i_{β} \end{matrix}];

8) instantaneous active power p and reactive power q is utilized to calculate average active power P and reactive power Q:

\{\begin{matrix} P (k) = P (k - 1) + \frac{1}{N} (p (k) - p (k - N)) \\ Q (k) = Q (k - 1) + \frac{1}{N} (q (k) - q (k - N)) \end{matrix};

Wherein k is present sample number of times；N is the total sampling number in a grid cycle；P (k) is the instantaneous of kth time sampling Active power；Q (k) is the instantaneous reactive power of kth time sampling；P (k) is the average active power of kth time sampling；Q(k) The average reactive power of kth time sampling；

9) utilize described average active power P and reactive power Q, be calculated reference voltage amplitude E by power droop control And angular frequency:

\{\begin{matrix} E = E^{*} - m Q \\ ω = ω^{*} - n P \end{matrix};

Wherein E^*、ω^*Representing the rated output voltage amplitude of three-phase inversion system and specified output angle frequency respectively, m, n divide Not for gain merit and idle sagging coefficient；

10) reference voltage amplitude E, angular frequency and phase place are utilizedCarry out three-phase voltage synthesis, obtain three-phase reference voltage

11) three-phase reference voltage that synthesis is obtainedTransform under α β coordinate system, obtain under α β coordinate system Reference voltage

12) by the electric current i under α β coordinate system_α、i_βIt is multiplied by virtual resistance, then the reference voltage that is added toOn, obtain standard Resonance PR controls the voltage reference value of outer voltageCurrent inner loop is obtained after being controlled by quasi-resonance PR Reference current

13) by the AC compounent under α β coordinate systemPhase place negates, the reference current of the current inner loop that is added toOn, Obtain reference current

14) by reference currentTransform under abc coordinate system, obtain the reference current of dead-beat current control Obtain three phase inverter bridge through track with zero error and drive dutycycle D of signal_a、D_b、D_c, by dutycycle D_a、D_b、 D_cIt is sent to Drive Protecting Circuit, produces and drive signal, be used for driving three-phase inversion system.

The multi-inverter parallel control method of quick harmonic circulating current the most according to claim 1 suppression, it is characterised in that Described step 2) in, the electric current i under α β coordinate system_α、i_βAnd the voltage u under α β coordinate system_α、u_βComputing formula is divided It is not:

[\begin{matrix} i_{α} \\ i_{β} \end{matrix}] = \sqrt{\frac{2}{3}} [\begin{matrix} 1 & - \frac{1}{2} & - \frac{1}{2} \\ 0 & \frac{\sqrt{3}}{2} & - \frac{\sqrt{3}}{2} \end{matrix}] [\begin{matrix} i_{a} \\ i_{b} \\ i_{c} \end{matrix}];

[\begin{matrix} u_{α} \\ u_{β} \end{matrix}] = \sqrt{\frac{2}{3}} [\begin{matrix} 1 & - \frac{1}{2} & - \frac{1}{2} \\ 0 & \frac{\sqrt{3}}{2} & - \frac{\sqrt{3}}{2} \end{matrix}] [\begin{matrix} u_{a} \\ u_{b} \\ u_{c} \end{matrix}] .

The multi-inverter parallel control method of quick harmonic circulating current the most according to claim 1 suppression, it is characterised in that Described step 3) in, the electric current i under rotating coordinate system_p、i_qComputing formula is:

[\begin{matrix} i_{p} \\ i_{q} \end{matrix}] = [\begin{matrix} {sinω}_{o} t & - {cosω}_{o} t \\ - {cosω}_{o} t & - {sinω}_{o} t \end{matrix}] [\begin{matrix} i_{α} \\ i_{β} \end{matrix}] .

The multi-inverter parallel control method of quick harmonic circulating current the most according to claim 1 suppression, it is characterised in that Described step 5) in, DC component electric currentComputing formula is:

[\begin{matrix} \overset{&OverBar;}{i_{α}} \\ \overset{&OverBar;}{i_{β}} \end{matrix}] = [\begin{matrix} {sinω}_{o} t & - {cosω}_{o} t \\ - {cosω}_{o} t & - {sinω}_{o} t \end{matrix}] [\begin{matrix} \overset{&OverBar;}{i_{p}} \\ \overset{&OverBar;}{i_{q}} \end{matrix}] .

The multi-inverter parallel control method of quick harmonic circulating current the most according to claim 1 suppression, it is characterised in that Described step 8) in, the computing formula of N is: N=round (λ f)；λ is the ratio of sample frequency and mains frequency.