CN104218590A - Unbalance voltage compensation and control method based on virtual synchronous machine - Google Patents

Abstract

Translated fromChinese

本发明公开了一种基于虚拟同步机的不平衡电压补偿控制方法。它采用基于陷波器滤波的功率计算方法，以消除一阶低通滤波器响应速度慢、稳定性差、无法消除不平衡负载带来的二次谐波等问题，计算出的有功和无功总功率作为下垂控制的反馈输入，并对产生的不平衡电压采用比例积分加谐振控制的方法抑制一部分不平衡电压，同时，采用一种不平衡电压补偿控制器，来进一步消除不平衡分量。它既能补偿不平衡电压，又能保持多机并联良好的均流度，可广泛地用于不平衡负载条件下的微网逆变器控制，以保持其离网运行时的输出电压平衡，并能多台并联运行。

The invention discloses an unbalanced voltage compensation control method based on a virtual synchronous machine. It adopts a power calculation method based on notch filter filtering to eliminate problems such as slow response speed, poor stability, and inability to eliminate the second harmonic caused by unbalanced loads of the first-order low-pass filter. The total active and reactive power calculated The power is used as the feedback input of the droop control, and the method of proportional integral plus resonance control is used to suppress part of the unbalanced voltage generated by the unbalanced voltage. At the same time, an unbalanced voltage compensation controller is used to further eliminate the unbalanced component. It can not only compensate unbalanced voltage, but also maintain good current sharing of multiple machines connected in parallel. It can be widely used in micro-grid inverter control under unbalanced load conditions to maintain output voltage balance when it is running off-grid. And multiple parallel operation.

Description

Translated fromChinese

基于虚拟同步机的不平衡电压补偿控制方法Unbalanced Voltage Compensation Control Method Based on Virtual Synchronous Machine

技术领域technical field

本发明涉及一种不平衡电压补偿控制方法，尤其是一种基于虚拟同步机的不平衡电压补偿控制方法。The invention relates to an unbalanced voltage compensation control method, in particular to an unbalanced voltage compensation control method based on a virtual synchronous machine.

背景技术Background technique

近年来，虚拟同步发电机技术作为微网逆变器的一种新型的发电模式，受到了学者的大量关注。采用虚拟同步发电机技术的微网逆变器叫做虚拟同步发电机。虚拟同步发电机(Virtual Synchronous Generator，VSG)需要运行在两种模式下，并网和孤岛并联运行。In recent years, virtual synchronous generator technology, as a new power generation mode of microgrid inverter, has received a lot of attention from scholars. The microgrid inverter using virtual synchronous generator technology is called virtual synchronous generator. Virtual synchronous generator (Virtual Synchronous Generator, VSG) needs to run in two modes, grid-connected and island parallel operation.

微网中存在大量的不平衡负荷，这些不平衡负荷会严重影响VSG的输出电压供电质量，引起输出电压不平衡，从而导致用电设备过电压等问题。为了达到良好的输出电压供电质量，要求将输出电压的不平衡度控制在一定的范围之内，同时保持多机并联良好的功率均分性能。There are a large number of unbalanced loads in the microgrid. These unbalanced loads will seriously affect the quality of the output voltage supply of the VSG, cause the output voltage to be unbalanced, and cause problems such as overvoltage of electrical equipment. In order to achieve a good output voltage power supply quality, it is required to control the unbalance degree of the output voltage within a certain range, and at the same time maintain the good power sharing performance of multi-machine parallel connection.

为此，人们做出了各种努力，如题为“A grid-interfacing power qualitycompensator for three-phase three-wire microgrid applications”，Li YW，Vilathgamuwa D M，Loh P C，《IEEE Transactions on PowerElectronics》,2006，21(4)，1021-1031(“应用于三相三线微网的并网功率质量补偿器”，《IEEE学报-电力电子期刊》，2006年第21卷第4期1021～1031页)的文章；该文给出了一种控制电压不平衡度的解决方案，是在供电端增加电能质量补偿装置APF(Active Power Filter)或者UPQC，这种控制方案增加了额外的装置，成本较高。To this end, various efforts have been made, such as entitled "A grid-interfacing power quality compensator for three-phase three-wire microgrid applications", Li YW, Vilathgamuwa D M, Loh P C, "IEEE Transactions on PowerElectronics", 2006 , 21(4), 1021-1031 ("Grid-connected power quality compensator for three-phase three-wire microgrid", "IEEE Journal-Journal of Power Electronics", Vol. 21, No. 4, pp. 1021-1031, 2006) Article; This article gives a solution to control voltage unbalance, which is to add power quality compensation device APF (Active Power Filter) or UPQC at the power supply end. This control scheme adds additional devices, and the cost is high.

题为“Autonomous voltage unbalance compensation in an IslandedDroop-controlled microgrid”，Savaghebi M，Jalilian A，Vasquez J C，et al，《IEEE Transactions on Industrial Electronics》，2013，60(4)，1390-1402(“应用于下垂控制微网孤岛模式的不平衡电压自动补偿器”，《IEEE学报-工业电子期刊》，2013年第60卷第4期1390～1402页)的文章；该文提出了一种谐振电压控制器来补偿不平衡电压，但是由于没有考虑虚拟阻抗上的不平衡电压降落等影响，补偿效果较差。Titled "Autonomous voltage unbalance compensation in an Islanded Droop-controlled microgrid", Savaghebi M, Jalilian A, Vasquez J C, et al, "IEEE Transactions on Industrial Electronics", 2013, 60(4), 1390-1402 ("applied to Unbalanced Voltage Automatic Compensator for Droop Control Microgrid Island Mode", "IEEE Transactions-Journal of Industrial Electronics", 2013, Vol. 60, No. 4, pp. 1390-1402); this paper proposes a resonant voltage controller To compensate the unbalanced voltage, but because the unbalanced voltage drop on the virtual impedance is not considered, the compensation effect is poor.

题为“Voltage unbalance and harmonics compensation for islandedmicrogrid inverters”，Liu Q，Tao Y，Liu X，et al，《Power ElectronicsIET》，2014，7(5)，1055-1063(“孤岛微网逆变器的电压不平衡和谐波补偿控制”，《IET工程技术学会-电力电子期刊》，2014年第7卷第5期1055～1063页)的文章；该文提出了采用多谐振控制器来抑制电压不平衡，但其控制带宽较窄，当微网系统频率变化时补偿效果较差。Titled "Voltage unbalance and harmonics compensation for islanded microgrid inverters", Liu Q, Tao Y, Liu X, et al, "Power Electronics IET", 2014, 7(5), 1055-1063 ("Voltage of islanded microgrid inverters Unbalance and Harmonic Compensation Control", "IET Engineering Technology Society-Power Electronics Journal", 2014, Vol. 7, No. 5, pp. 1055-1063); this paper proposes the use of multi-resonant controllers to suppress voltage unbalance , but its control bandwidth is narrow, and the compensation effect is poor when the frequency of the microgrid system changes.

题为“A method of three-phase balancing in microgrid by photovoltaicgeneration system”，Hojo M，Iwase Y，Funabashi T，et al，《PowerElectronics and Motion Control Conference2008.EPE-PEMC》，2008，13th.IEEE，2008，2487-2491(“光伏发电微网系统中的三相平衡控制策略”，《第十三届电力电子与运动控制国际会议》，2008年第13期2487～2491页)的文章；该文提出了采用注入负序电流的方法来补偿不平衡电压，然而在严酷的条件下负序电流的注入会使得微网逆变器过流导致关机。Titled "A method of three-phase balancing in microgrid by photovoltaicgeneration system", Hojo M, Iwase Y, Funabashi T, et al, "Power Electronics and Motion Control Conference2008.EPE-PEMC", 2008, 13th.IEEE, 2008, 2487 -2491 ("Three-phase Balance Control Strategy in Photovoltaic Power Generation Micro-grid System", "The Thirteenth International Conference on Power Electronics and Motion Control", Issue 13, 2008, pp. 2487-2491); The method of injecting negative sequence current is used to compensate the unbalanced voltage. However, under severe conditions, the injection of negative sequence current will cause the microgrid inverter to overcurrent and cause shutdown.

综上所述，现有技术均未能解决在微网逆变器并联运行系统中，带不平衡负载时，既能保证输出电压良好的平衡度又能保证孤岛运行时的逆变器并联均流问题。To sum up, none of the existing technologies can solve the problem of ensuring a good balance of the output voltage and ensuring the parallel balance of the inverters during island operation in the microgrid inverter parallel operation system with unbalanced loads. flow problem.

发明内容Contents of the invention

本发明要解决的技术问题为克服上述各种技术方案的局限性，针对虚拟同步发电机离网并联运行时，带不平衡负载的输出电压不平衡问题，提供一种既能补偿不平衡电压，又能保持多机并联良好的均流度的基于虚拟同步机的不平衡电压补偿控制方法。The technical problem to be solved by the present invention is to overcome the limitations of the above-mentioned various technical solutions, aiming at the problem of unbalanced output voltage with unbalanced load when the virtual synchronous generator is running off-grid in parallel, to provide a method that can compensate unbalanced voltage, It is also an unbalanced voltage compensation control method based on virtual synchronous machines that can maintain good current sharing of multiple machines in parallel.

为解决本发明的技术问题，所采用的技术方案为：基于虚拟同步机的不平衡电压补偿控制方法包括微网逆变器输出电容电压的采集，特别是主要步骤如下：In order to solve the technical problem of the present invention, the technical solution adopted is: the unbalanced voltage compensation control method based on the virtual synchronous machine includes the collection of the output capacitor voltage of the microgrid inverter, especially the main steps are as follows:

步骤1，先采集微网逆变器的输出电容电压U_ca,U_cb,U_cc、桥臂侧电感电流I_la,I_lb,I_lc和输出电流I_ox，经过单同步旋转坐标变换得到输出电容电压dq的分量U_cd,U_cq、桥臂侧电感电流dq的分量I_ld,I_lq和输出电流dq的分量I_od,I_oq，再利用输出电容电压U_ca,U_cb,U_cc和桥臂侧电感电流I_la,I_lb,I_lc，经过双同步旋转坐标变换得到电容电压的负序分量U_CN-d,U_CN-q和电感电流的负序分量I_LN-d,I_LN-q；Step 1, first collect the output capacitor voltage U_ca , U_cb , U_cc of the microgrid inverter, the inductor current I_la , I_lb , I_lc of the bridge arm side and the output current I_ox , and obtain the output through single synchronous rotation coordinate transformation The components of capacitor voltage dq U_cd , U_cq , the components of bridge arm side inductor current dq I_ld , I_lq and the components of output current dq I_od , I_oq , and then use the output capacitor voltages U_ca , U_cb , U_cc and The inductance current I_la , I_lb , I_lc on the bridge arm side, through double synchronous rotation coordinate transformation, the negative sequence components U_CN-d , U_CN-q of the capacitor voltage and the negative sequence components I_LN-d , I_LN of the inductor current are obtained_-q ;

步骤2，根据步骤1中得到的输出电容电压dq的分量U_cd,U_cq和输出电流dq的分量I_od,I_oq，经过有功功率计算方程和无功功率计算方程得到平均有功功率和平均无功功率Step 2, according to the components U_cd , U_cq of the output capacitor voltage dq obtained in step 1 and the components I_od , I_oq of the output current dq, the average active power is obtained through the active power calculation equation and the reactive power calculation equation and average reactive power

步骤3，根据步骤2中得到的平均有功功率和微网逆变器给定的有功功率指令P_ref、微网逆变器给定的角频率指令ω_ref，经过功角控制方程得到虚拟同步发电机的角频率ω，对角频率ω积分得到虚拟同步机的矢量角θ；Step 3, according to the average active power obtained in step 2 and the active power command P_ref given by the microgrid inverter, the angular frequency command ω_ref given by the microgrid inverter, the angular frequency ω of the virtual synchronous generator is obtained through the power angle control equation, and the angular frequency ω is integrated to obtain The vector angle θ of the virtual synchronous machine;

步骤4，根据步骤2中得到的平均无功功率和微网逆变器给定的无功功率指令Q_ref、电压指令U_ref，经过无功控制方程得到虚拟同步机的端电压U^*；Step 4, according to the average reactive power obtained in step 2 and the reactive power command Q_ref and voltage command U_ref given by the microgrid inverter, and the terminal voltage U^* of the virtual synchronous machine is obtained through the reactive power control equation;

步骤5，先根据步骤4中得到的端电压U^*和步骤1中得到的U_cd,U_cq，通过电压控制方程得到电容电流指令信号再根据电容电流指令信号和步骤1中的桥臂侧电感电流dq的分量I_ld,I_lq和输出电流dq的分量I_od,I_oq，通过电流控制方程得到控制信号U_d1,U_q1；Step 5. First, according to the terminal voltage U^* obtained in step 4 and U_cd , U_cq obtained in step 1, obtain the capacitor current command signal through the voltage control equation Then according to the capacitor current command signal And the components I_ld , I_lq of the bridge arm side inductor current dq in step 1 and the components I_od , I_oq of the output current dq, the control signals U_d1 , U_q1 are obtained through the current control equation;

步骤6，根据步骤1中得到的电容电压的负序分量U_CN-d,U_CN-q和电感电流的负序分量I_LN-d,I_LN-q，经过负序电压补偿控制方程得到控制信号U_d2,U_q2；Step 6, according to the negative sequence components U_CN-d , U_CN-q of the capacitor voltage obtained in step 1 and the negative sequence components I_LN-d , I_LN-q of the inductor current, it is controlled through the negative sequence voltage compensation control equation signal U_d2 , U_q2 ;

步骤7，将步骤5和步骤6中得到的控制信号U_d1,U_q1和U_d2,U_q2分别相加得到控制信号U_d,U_q；Step 7, adding the control signals U_d1 , U_q1 and U_d2 , U_q2 obtained in step 5 and step 6 respectively to obtain control signals U_d , U_q ;

步骤8，先根据步骤7中的控制信号U_d,U_q和步骤3中得到的矢量角θ，经过单同步旋转坐标反变换得到三相桥臂电压控制信号U_a,U_b,U_c，再根据U_a,U_b,U_c生成微网逆变器逆变桥开关管的PWM控制信号。Step 8: First, according to the control signals U_d , U_q in step 7 and the vector angle θ obtained in step 3, the three-phase bridge arm voltage control signals U_a , U_b , U_c are obtained through inverse transformation of single synchronous rotating coordinates, Then according to U_a , U_b , U_c generate the PWM control signal of the switching tube of the inverter bridge of the microgrid inverter.

作为基于虚拟同步机的不平衡电压补偿控制方法的进一步改进：As a further improvement of the unbalanced voltage compensation control method based on virtual synchronous machine:

优选地，步骤2中的有功功率计算方程为Preferably, the active power calculation equation in step 2 is

$\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>P</span>P</span>}}<span><span>=</span>=</span><span><span>(</span>(</span>\underset{\mathrm{<span><span>h</span>h</span>}}{\mathrm{<span><span>\&Pi;</span>\&Pi;</span>}}\frac{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>)</span>)</span><span><span>\&CenterDot;</span>\&CenterDot;</span>\frac{\mathrm{<span><span>1.5</span>1.5</span>}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>\&CenterDot;</span>\&CenterDot;</span><span><span>(</span>(</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中，Q为谐振控制器品质因数、ω_h为陷波器需要滤除的谐波角频率、s为拉普拉斯算子、τ为一阶低通滤波器的时间常数。Among them, Q is the quality factor of the resonance controller, ω_h is the harmonic angular frequency that needs to be filtered out by the notch filter, s is the Laplacian operator, and τ is the time constant of the first-order low-pass filter.

优选地，步骤2中的无功功率计算方程为Preferably, the reactive power calculation equation in step 2 is

$\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>Q</span>Q</span>}}<span><span>=</span>=</span><span><span>(</span>(</span>\underset{\mathrm{<span><span>h</span>h</span>}}{\mathrm{<span><span>\&Pi;</span>\&Pi;</span>}}\frac{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>)</span>)</span><span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{\mathrm{<span><span>1.5</span>1.5</span>}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>\&CenterDot;</span>\&CenterDot;</span><span><span>(</span>(</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中，Q为谐振控制器品质因数、ω_h为陷波器需要滤除的谐波角频率、s为拉普拉斯算子、τ为一阶低通滤波器的时间常数。Among them, Q is the quality factor of the resonance controller, ω_h is the harmonic angular frequency that needs to be filtered out by the notch filter, s is the Laplacian operator, and τ is the time constant of the first-order low-pass filter.

优选地，步骤3中的功角控制方程为Preferably, the power angle control equation in step 3 is

$\mathrm{<span><span>\&omega;</span>\&omega;</span>}<span><span>=</span>=</span>{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>m</span>m</span>}}{\mathrm{<span><span>J</span>J</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>-</span>-</span>\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>P</span>P</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中，ω_ref为微网逆变器给定有功功率指令P_ref时的额定角频率、m为功角控制下垂系数、J为模拟同步发电机机组的虚拟转动惯量时间常数、ω₀为电网固定角频率。Among them, ω_ref is the rated angular frequency when the microgrid inverter gives the active power command Pre_ref , m is the power angle control droop coefficient, J is the virtual moment of inertia time constant of the simulated synchronous generator set, and ω₀ is the grid fixed Angular frequency.

优选地，步骤4中无功控制方程为Preferably, the reactive control equation in step 4 is

${\mathrm{<span><span>U</span>u</span>}}^{<span><span>*</span>*</span>}<span><span>=</span>=</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>+</span>+</span>\mathrm{<span><span>n</span>no</span>}<span><span>(</span>(</span>{\mathrm{<span><span>Q</span>Q</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>-</span>-</span>\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>Q</span>Q</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中，U_ref为微网逆变器给定无功功率指令Q_ref时的额定输出电容电压、n为功角控制下垂系数。Among them, U_ref is the rated output capacitor voltage when the reactive power command Q_ref is given by the microgrid inverter, and n is the power angle control droop coefficient.

优选地，步骤5中的电压控制方程为Preferably, the voltage control equation in step 5 is

$I_{\mathrm{cd}}^{*}=K_p+K_i/s+\frac{K_{r}s}{s^2+2Q{\mathrm{\&omega;}}_{0}s+{\left(2{\mathrm{\&omega;}}_0\right)}^2}(U^{*}-U_{\mathrm{cd}})$，$I_{\mathrm{cd}}^{*}=K_p+K_i/\mathrm{the\; s}+\frac{K_r\mathrm{the\; s}}{{\mathrm{the\; s}}^2+2Q{\mathrm{\&omega;}}_0\mathrm{the\; s}+{\left(2{\mathrm{\&omega;}}_0\right)}^2}(u^{*}-u_{\mathrm{cd}})$ ,

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}^{<span><span>*</span>*</span>}<span><span>=</span>=</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>p</span>p</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>i</span>i</span>}}<span><span>/</span>/</span>\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>\frac{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>r</span>r</span>}}\mathrm{<span><span>s</span>the\; s</span>}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{<span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>(</span>(</span>\mathrm{<span><span>0</span>0</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}<span><span>)</span>)</span>$

其中，K_p为比例控制系数、K_i为积分控制系数、K_r为谐振控制器比例系数。Among them, K_p is the proportional control coefficient, K_i is the integral control coefficient, and K_r is the proportional coefficient of the resonance controller.

优选地，步骤5中的电流控制方程为Preferably, the current control equation in step 5 is

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>d</span>d</span>}\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>\mathrm{<span><span>K</span>K</span>}<span><span>(</span>(</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}^{<span><span>*</span>*</span>}<span><span>-</span>-</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>ld</span>ld</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span>$

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>q</span>q</span>}\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>\mathrm{<span><span>K</span>K</span>}<span><span>(</span>(</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}^{<span><span>*</span>*</span>}<span><span>-</span>-</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>lq</span>lq</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中，K为比例控制系数。Among them, K is the proportional control coefficient.

优选地，步骤6中的负序电压补偿控制方程为Preferably, the negative sequence voltage compensation control equation in step 6 is

$U_{d2}=\frac{K_1(0-U_{C\_N-d})-K_2{\mathrm{\&omega;}}_0{\mathrm{LI}}_{L\_N-q}}{\mathrm{\&tau;s}+1}$，$u_{d2}=\frac{K_1(0-u_{C\_N-d})-K_2{\mathrm{\&omega;}}_0{\mathrm{LI}}_{L\_N-q}}{\mathrm{\&tau;s}+1}$ ,

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>q</span>q</span>}\mathrm{<span><span>2</span>2</span>}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>(</span>(</span>\mathrm{<span><span>0</span>0</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>C</span>C</span>}<span><span>\_</span>\_</span>\mathrm{<span><span>N</span>N</span>}<span><span>-</span>-</span>\mathrm{<span><span>q</span>q</span>}}<span><span>)</span>)</span><span><span>-</span>-</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}{\mathrm{<span><span>LI</span>LI</span>}}_{\mathrm{<span><span>L</span>L</span>}<span><span>\_</span>\_</span>\mathrm{<span><span>N</span>N</span>}<span><span>-</span>-</span>\mathrm{<span><span>d</span>d</span>}}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}$

其中，K₁为电压补偿系数、K₂为电流补偿系数、L为微网逆变器桥臂侧电感值、τ为滤波时间常数。Among them, K₁ is the voltage compensation coefficient, K₂ is the current compensation coefficient, L is the inductance value of the bridge arm side of the microgrid inverter, and τ is the filter time constant.

相对于现有技术的有益效果是：Compared with the beneficial effects of the prior art, it is:

采用本发明后，虚拟同步发电机运行时在既能补偿不平衡电压，又能保持多机并联良好的均流度的基础上，具有了如下优点：After adopting the present invention, the virtual synchronous generator can not only compensate the unbalanced voltage, but also maintain a good current equalization degree of multi-machine parallel connection during operation, and has the following advantages:

1.不需要增加额外的装置，降低了制造和运行的成本。1. There is no need to add additional devices, which reduces the cost of manufacture and operation.

2.解决了阻抗上的不平衡电压降落的难题。2. Solve the problem of unbalanced voltage drop on the impedance.

3.仅增加一个补偿控制算法，就解决了控制带宽窄的问题。3. Only one compensation control algorithm is added to solve the problem of narrow control bandwidth.

4.不需要注入负序电流，杜绝了过流的产生。4. There is no need to inject negative sequence current, which prevents the generation of overcurrent.

附图说明Description of drawings

图1是本发明的一种基本控制框图。Fig. 1 is a kind of basic control block diagram of the present invention.

图2是本发明的总体控制框图。Fig. 2 is the overall control block diagram of the present invention.

图3是本发明所采用的虚拟同步发电机的拓扑结构图。Fig. 3 is a topological structure diagram of the virtual synchronous generator adopted in the present invention.

图4是本发明中平均有功功率和平均无功功率计算方法框图。Fig. 4 is a block diagram of the calculation method of average active power and average reactive power in the present invention.

具体实施方式Detailed ways

下面结合附图对本发明的优选方式作进一步详细的描述。The preferred modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

本发明实施时的有关电气参数设置如下：The relevant electrical parameters when the present invention is implemented are set as follows:

虚拟同步发电机的直流母线电压Udc为550V，输出交流线电压有效值为380V/50Hz，额定容量为100KW，交流电压滤波电感为0.5mH，滤波电容为200μF。变压器为100KVA270/400V的Dyn11型变压器。The DC bus voltage Udc of the virtual synchronous generator is 550V, the effective value of the output AC line voltage is 380V/50Hz, the rated capacity is 100KW, the AC voltage filter inductance is 0.5mH, and the filter capacitor is 200μF. The transformer is a Dyn11 type transformer of 100KVA270/400V.

参见图1、图2、图3和图4，本发明的实施过程如下：Referring to Fig. 1, Fig. 2, Fig. 3 and Fig. 4, the implementation process of the present invention is as follows:

步骤1，先采集微网逆变器的输出电容电压U_ca,U_cb,U_cc、桥臂侧电感电流I_la,I_lb,I_lc和输出电流I_ox，经过单同步旋转坐标变换得到输出电容电压dq的分量U_cd,U_cq、桥臂侧电感电流dq的分量I_ld,I_lq和输出电流dq的分量I_od,I_oq。再利用输出电容电压U_ca,U_cb,U_cc和桥臂侧电感电流I_la,I_lb,I_lc，经过双同步旋转坐标变换得到电容电压的负序分量U_CN-d,U_CN-q和电感电流的负序分量I_LN-d,I_LN-q。Step 1, first collect the output capacitor voltage U_ca , U_cb , U_cc of the microgrid inverter, the inductor current I_la , I_lb , I_lc of the bridge arm side and the output current I_ox , and obtain the output through single synchronous rotation coordinate transformation The components U_cd , U_cq of the capacitor voltage dq, the components I_ld , I_lq of the bridge arm side inductor current dq and the components I_od , I_oq of the output current dq. Then use the output capacitor voltage U_ca , U_cb , U_cc and the bridge arm side inductor current I_la , I_lb , I_lc to obtain the negative sequence components U_CN-d , U_CN-q of the capacitor voltage through double synchronous rotating coordinate transformation And the negative sequence components of the inductor current I_LN-d , I_LN-q .

步骤2，根据步骤1中得到的输出电容电压dq的分量U_cd,U_cq和输出电流dq的分量I_od,I_oq，经过有功功率计算方程和无功功率计算方程得到平均有功功率和平均无功功率其中，Step 2, according to the components U_cd , U_cq of the output capacitor voltage dq obtained in step 1 and the components I_od , I_oq of the output current dq, the average active power is obtained through the active power calculation equation and the reactive power calculation equation and average reactive power in,

有功功率计算方程为The active power calculation equation is

$\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>P</span>P</span>}}<span><span>=</span>=</span><span><span>(</span>(</span>\underset{\mathrm{<span><span>h</span>h</span>}}{\mathrm{<span><span>\&Pi;</span>\&Pi;</span>}}\frac{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>)</span>)</span><span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{\mathrm{<span><span>1.5</span>1.5</span>}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span><span><span>(</span>(</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中的Q为谐振控制器品质因数、ω_h为陷波器需要滤除的谐波角频率、s为拉普拉斯算子、τ为一阶低通滤波器的时间常数；Among them, Q is the quality factor of the resonance controller, ω_h is the harmonic angular frequency that needs to be filtered out by the notch filter, s is the Laplacian operator, and τ is the time constant of the first-order low-pass filter;

无功功率计算方程为The reactive power calculation equation is

$\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>Q</span>Q</span>}}<span><span>=</span>=</span><span><span>(</span>(</span>\underset{\mathrm{<span><span>h</span>h</span>}}{\mathrm{<span><span>\&Pi;</span>\&Pi;</span>}}\frac{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>h</span>h</span>}}}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>)</span>)</span><span><span>\&CenterDot;</span>\&Center\; Dot;</span>\frac{\mathrm{<span><span>1.5</span>1.5</span>}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>\&CenterDot;</span>\&Center\; Dot;</span><span><span>(</span>(</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中的Q为谐振控制器品质因数、ω_h为陷波器需要滤除的谐波角频率、s为拉普拉斯算子、τ为一阶低通滤波器的时间常数。Among them, Q is the quality factor of the resonance controller, ω_h is the harmonic angular frequency that needs to be filtered out by the notch filter, s is the Laplacian operator, and τ is the time constant of the first-order low-pass filter.

在本实施例中，考虑主要滤除的谐波次数为2次和3次谐波，因此选取h＝2,3，此时ω_h＝628.3186rad/s,942.4779rad/s一阶低通滤波器主要考虑滤除高次谐波，且不影响动态响应，一般取τ≤2e^-3s，本案例取值τ＝1.5e^-4s；品质因数Q主要考虑陷波器的滤波效果，在本案例中，选取Q＝0.5。In this embodiment, consider that the main harmonics to be filtered out are the 2nd and 3rd harmonics, so h=2, 3 is selected, at this time ω_h =628.3186rad/s, 942.4779rad/s first-order low-pass filter The filter is mainly considered to filter out high-order harmonics without affecting the dynamic response. Generally, τ≤2e^-3 s is taken, and the value in this case is τ=1.5e^-4 s; the quality factor Q mainly considers the filtering effect of the notch filter. In this case, select Q=0.5.

平均有功功率和平均无功功率的计算框图如图4所示。The calculation block diagram of average active power and average reactive power is shown in Figure 4.

步骤3，根据步骤2中得到的平均有功功率和微网逆变器给定的有功功率指令P_ref、微网逆变器给定的角频率指令ω_ref，经过功角控制方程得到虚拟同步发电机的角频率ω，对角频率ω积分得到虚拟同步机的矢量角θ；其中，Step 3, according to the average active power obtained in step 2 and the active power command P_ref given by the microgrid inverter, the angular frequency command ω_ref given by the microgrid inverter, the angular frequency ω of the virtual synchronous generator is obtained through the power angle control equation, and the angular frequency ω is integrated to obtain The vector angle θ of the virtual synchronous machine; where,

功角控制方程为The power angle governing equation is

$\mathrm{<span><span>\&omega;</span>\&omega;</span>}<span><span>=</span>=</span>{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>+</span>+</span>\frac{\mathrm{<span><span>m</span>m</span>}}{\mathrm{<span><span>J</span>J</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>-</span>-</span>\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>P</span>P</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中的ω_ref为微网逆变器给定有功功率指令P_ref时的额定角频率、m为功角控制下垂系数、J为模拟同步发电机机组的虚拟转动惯量时间常数、ω₀为电网固定角频率。Among them,_ωref is the rated angular frequency when the microgrid inverter gives the active power command P_ref , m is the power angle control droop coefficient, J is the virtual moment of inertia time constant of the simulated synchronous generator set, and_ω0 is the grid fixed Angular frequency.

功角控制方程表明了微网逆变器有功功率下垂曲线关系和虚拟惯量大小。其中，虚拟惯量标明了系统频率的变化率，为了保证系统频率变化平稳，需要有较大的虚拟惯量；然而虚拟惯量相当于在系统中加入了一阶惯性环节，太大的虚拟惯量有可能导致系统的不稳定。因而参数选择需要折中处理。为保证系统稳定性，在本实施例中，惯性时间常数范围在τ_virtual＝Jω₀m≤2e^-3s；功角控制方程中的有功功率下垂曲线关系包括三个系数，功角控制下垂系数m表示下垂曲线的斜率，取值原则为100％的有功功率变化时，频率变化0.5Hz以内；给定有功功率指令P_ref和相对应的额定角频率ω_ref表示下垂曲线的位置关系，主要考虑微网逆变器输出有功功率为P_ref时，其输出频率大小；The control equation of the power angle shows the drooping curve relationship of the active power of the microgrid inverter and the magnitude of the virtual inertia. Among them, the virtual inertia indicates the change rate of the system frequency. In order to ensure the smooth change of the system frequency, a large virtual inertia is required; however, the virtual inertia is equivalent to adding a first-order inertia link to the system, and too large virtual inertia may cause System instability. Therefore, parameter selection requires a compromise. In order to ensure system stability, in this embodiment, the inertia time constant range is τ_virtual = Jω₀ m≤2e^-3 s; the active power droop curve relationship in the power angle control equation includes three coefficients, and the power angle control droop coefficient m represents the slope of the droop curve, and the value principle is that when the active power changes by 100%, the frequency changes within 0.5Hz; the given active power command P_ref and the corresponding rated angular frequency ω_ref represent the position relationship of the droop curve, mainly considered When the output active power of the microgrid inverter is_Pref , its output frequency;

在本实施例中，电网角频率采用额定频率为50Hz时对应的角频率，即ω₀＝314.1593rad/s，功角控制下垂系数取值为根据惯性时间常数取值原则取τ_virtual＝Jω₀m＝1.5e^-3s，可得J＝0.2Kg·m²,为保证控制运行时能量不流向直流侧，给定有功功率指令取值为P_ref＝1KW，此时对应的额定角频率取值为ω_ref＝314.1593rad/s。In this embodiment, the grid angular frequency adopts the corresponding angular frequency when the rated frequency is 50Hz, that is, ω₀ =314.1593rad/s, and the power angle control droop coefficient is According to the value principle of the inertia time constant, take τ_virtual = Jω₀ m = 1.5e^-3 s to get J = 0.2Kg·m² , in order to ensure that the energy does not flow to the DC side during the control operation, the given active power command value is P_ref =1KW, and the corresponding rated angular frequency at this time is ω_ref =314.1593rad/s.

步骤4，根据步骤2中得到的平均无功功率和微网逆变器给定的无功功率指令Q_ref、电压指令U_ref，经过无功控制方程得到虚拟同步机的端电压U^*；其中，Step 4, according to the average reactive power obtained in step 2 and the reactive power command Q_ref and voltage command U_ref given by the microgrid inverter, the terminal voltage U^* of the virtual synchronous machine is obtained through the reactive power control equation; where,

无功控制方程为The reactive control equation is

${\mathrm{<span><span>U</span>u</span>}}^{<span><span>*</span>*</span>}<span><span>=</span>=</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>+</span>+</span>\mathrm{<span><span>n</span>no</span>}<span><span>(</span>(</span>{\mathrm{<span><span>Q</span>Q</span>}}_{\mathrm{<span><span>ref</span>ref</span>}}<span><span>-</span>-</span>\stackrel{<span><span>\&OverBar;</span>\&OverBar;</span>}{\mathrm{<span><span>Q</span>Q</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中的U_ref为微网逆变器给定无功功率指令Q_ref时的额定输出电容电压、n为功角控制下垂系数。Among them, U_ref is the rated output capacitor voltage when the reactive power command Q_ref is given by the microgrid inverter, and n is the power angle control droop coefficient.

无功控制下垂系数n取值原则为100％的无功功率变化时，电压幅值变化在2％之内；给定无功功率指令Q_ref和相对应的额定输出电容电压U_ref表示下垂曲线的位置关系，主要考虑微网逆变器输出无功功率为Q_ref时，其输出电压大小。The value principle of the reactive power control droop coefficient n is that when the reactive power changes by 100%, the voltage amplitude changes within 2%; the given reactive power command Q_ref and the corresponding rated output capacitor voltage U_ref represent the droop curve The positional relationship of the microgrid inverter mainly considers the output voltage of the microgrid inverter when the output reactive power is_Qref .

在本实施例中，无功控制下垂系数取值为给定无功功率指令Q_ref考虑系统输出无功功率为Q_ref＝0，此时对应的额定输出电容电压U_ref＝380V。In this embodiment, the value of reactive power control droop coefficient is The given reactive power command Q_ref considers that the system output reactive power is Q_ref =0, and the corresponding rated output capacitor voltage U_ref =380V at this time.

步骤5，先根据步骤4中得到的端电压U*和步骤1中得到的U_cd,U_cq，通过电压控制方程得到电容电流指令信号其中，Step 5. First, according to the terminal voltage U* obtained in step 4 and U_cd , U_cq obtained in step 1, obtain the capacitor current command signal through the voltage control equation in,

电压控制方程为The voltage governing equation is

$I_{\mathrm{cd}}^{*}=K_p+K_i/s+\frac{K_{r}s}{s^2+2Q{\mathrm{\&omega;}}_{0}s+{\left(2{\mathrm{\&omega;}}_0\right)}^2}(U^{*}-U_{\mathrm{cd}})$，$I_{\mathrm{cd}}^{*}=K_p+K_i/\mathrm{the\; s}+\frac{K_r\mathrm{the\; s}}{{\mathrm{the\; s}}^2+2Q{\mathrm{\&omega;}}_0\mathrm{the\; s}+{\left(2{\mathrm{\&omega;}}_0\right)}^2}(u^{*}-u_{\mathrm{cd}})$ ,

${\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}^{<span><span>*</span>*</span>}<span><span>=</span>=</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>p</span>p</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>i</span>i</span>}}<span><span>/</span>/</span>\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>\frac{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>r</span>r</span>}}\mathrm{<span><span>s</span>the\; s</span>}}{{\mathrm{<span><span>s</span>the\; s</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>Q</span>Q</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}\mathrm{<span><span>s</span>the\; s</span>}<span><span>+</span>+</span>{<span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}}<span><span>(</span>(</span>\mathrm{<span><span>0</span>0</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}<span><span>)</span>)</span>$

其中的K_p为比例控制系数、K_i为积分控制系数、K_r为谐振控制器比例系数。Among them, K_p is the proportional control coefficient, K_i is the integral control coefficient, and K_r is the proportional coefficient of the resonance controller.

再根据电容电流指令信号和步骤1中的桥臂侧电感电流dq的分量I_ld,I_lq和输出电流dq的分量I_od,I_oq，通过电流控制方程得到控制信号U_d1,U_q1；其中，Then according to the capacitor current command signal And the components I_ld , I_lq of the bridge arm side inductor current dq in step 1 and the components I_od , I_oq of the output current dq, the control signals U_d1 , U_q1 are obtained through the current control equation; where,

电流控制方程为The current governing equation is

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>d</span>d</span>}\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>\mathrm{<span><span>K</span>K</span>}<span><span>(</span>(</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cd</span>cd</span>}}^{<span><span>*</span>*</span>}<span><span>-</span>-</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>ld</span>ld</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>od</span>od</span>}}<span><span>)</span>)</span>$

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>q</span>q</span>}\mathrm{<span><span>1</span>1</span>}}<span><span>=</span>=</span>\mathrm{<span><span>K</span>K</span>}<span><span>(</span>(</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>cq</span>cq</span>}}^{<span><span>*</span>*</span>}<span><span>-</span>-</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>lq</span>lq</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>I</span>I</span>}}_{\mathrm{<span><span>oq</span>oq</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

其中的K为比例控制系数。Among them, K is the proportional control coefficient.

电压和电流控制方程中的参数主要考虑控制系统的稳定性和动稳态性能；在本实施例中，取K_p＝0.03,K_i＝0.8,K_r＝120,Q＝16,K＝0.05。The parameters in the voltage and current control equations mainly consider the stability and dynamic steady-state performance of the control system; in this embodiment, K_p =0.03, K_i =0.8, K_r =120, Q=16, K=0.05 .

步骤1～5的控制过程可参见图1。See Figure 1 for the control process of steps 1-5.

步骤6，根据步骤1中得到的电容电压的负序分量U_CN-d,U_CN-q和电感电流的负序分量I_LN-d,I_LN-q，经过负序电压补偿控制方程得到控制信号U_d2,U_q2；其中，Step 6, according to the negative sequence components U_CN-d , U_CN-q of the capacitor voltage obtained in step 1 and the negative sequence components I_LN-d , I_LN-q of the inductor current, it is controlled through the negative sequence voltage compensation control equation Signal U_d2 , U_q2 ; where,

负序电压补偿控制方程为The control equation of negative sequence voltage compensation is

$U_{d2}=\frac{K_1(0-U_{C\_N-d})-K_2{\mathrm{\&omega;}}_0{\mathrm{LI}}_{L\_N-q}}{\mathrm{\&tau;s}+1}$，$u_{d2}=\frac{K_1(0-u_{C\_N-d})-K_2{\mathrm{\&omega;}}_0{\mathrm{LI}}_{L\_N-q}}{\mathrm{\&tau;s}+1}$ ,

${\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>q</span>q</span>}\mathrm{<span><span>2</span>2</span>}}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>(</span>(</span>\mathrm{<span><span>0</span>0</span>}<span><span>-</span>-</span>{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>C</span>C</span>}<span><span>\_</span>\_</span>\mathrm{<span><span>N</span>N</span>}<span><span>-</span>-</span>\mathrm{<span><span>q</span>q</span>}}<span><span>)</span>)</span><span><span>-</span>-</span>{\mathrm{<span><span>K</span>K</span>}}_{\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}_{\mathrm{<span><span>0</span>0</span>}}{\mathrm{<span><span>LI</span>LI</span>}}_{\mathrm{<span><span>L</span>L</span>}<span><span>\_</span>\_</span>\mathrm{<span><span>N</span>N</span>}<span><span>-</span>-</span>\mathrm{<span><span>d</span>d</span>}}}{\mathrm{<span><span>\&tau;s</span>\&tau;s</span>}<span><span>+</span>+</span>\mathrm{<span><span>1</span>1</span>}}$

其中的K₁为电压补偿系数、K₂为电流补偿系数、L为微网逆变器桥臂侧电感值、τ为滤波时间常数。Among them, K₁ is the voltage compensation coefficient, K₂ is the current compensation coefficient, L is the inductance value of the bridge arm side of the microgrid inverter, and τ is the filter time constant.

补偿系数主要考虑动态输出阻抗补偿的有效性，一般取值0.5≤K₁＝K₂≤1。为了滤除电容电压的负序分量U_CN-d,U_CN-q和电感电流的负序分量I_LN-d,I_LN-q的谐波分量，考虑一阶低通滤波器的时间常数τ≤2e^-3s。在本实施例中，取K₁＝1、K₂＝1、τ＝0.00115。The compensation coefficient mainly considers the effectiveness of dynamic output impedance compensation, and generally takes a value of 0.5≤K₁ =K₂ ≤1. In order to filter the harmonic components of the negative sequence components U_CN-d , U_CN-q of the capacitor voltage and the negative sequence components I_LN-d and I_LN-q of the inductor current, consider the time constant τ of the first-order low-pass filter ≤2e^-3 s. In this embodiment, K₁ =1, K₂ =1, τ=0.00115.

步骤7，将步骤5和步骤6中得到的控制信号U_d1,U_q1和U_d2,U_q2分别相加得到控制信号U_d,U_q；Step 7, adding the control signals U_d1 , U_q1 and U_d2 , U_q2 obtained in step 5 and step 6 respectively to obtain control signals U_d , U_q ;

步骤8，先根据步骤7中的控制信号U_d,U_q和步骤3中得到的矢量角θ，经过单同步旋转坐标反变换得到三相桥臂电压控制信号U_a,U_b,U_c，再根据U_a,U_b,U_c生成微网逆变器逆变桥开关管的PWM控制信号。Step 8: First, according to the control signals U_d , U_q in step 7 and the vector angle θ obtained in step 3, the three-phase bridge arm voltage control signals U_a , U_b , U_c are obtained through inverse transformation of single synchronous rotating coordinates, Then according to U_a , U_b , U_c generate the PWM control signal of the switching tube of the inverter bridge of the microgrid inverter.

显然，本领域的技术人员可以对本发明的基于虚拟同步机的不平衡电压补偿控制方法进行各种改动和变型而不脱离本发明的精神和范围。这样，倘若对本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内，则本发明也意图包含这些改动和变型在内。Apparently, those skilled in the art can make various changes and modifications to the virtual synchronous machine-based unbalanced voltage compensation control method of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (8)

1. The unbalanced voltage compensation control method based on the virtual synchronous machine comprises the acquisition of the output capacitor voltage of the microgrid inverter, and is characterized by mainly comprising the following steps of:

step 1, firstly, acquiring output capacitor voltage U of the microgrid inverter_ca,U_cb,U_ccBridge arm side induction current I_la,I_lb,I_lcAnd an output current I_oxObtaining the component U of the output capacitor voltage dq through the transformation of the single synchronous rotation coordinate_cd,U_cqComponent I of bridge arm side inductor current dq_ld,I_lqAnd a component I of the output current dq_od,I_oqReuse of output capacitor voltage U_ca,U_cb,U_ccAnd bridge arm side inductor current I_la,I_lb,I_lcObtaining the negative sequence component U of the capacitor voltage through double synchronous rotation coordinate transformation_{C_N-d},U_{C_N-q}And the negative sequence component I of the inductor current_{L_N-d},I_{L_N-q}；

Step 2, according to the component U of the output capacitor voltage dq obtained in the step 1_cd,U_cqAnd a component I of the output current dq_od,I_oqObtaining the average active power through an active power calculation equation and a reactive power calculation equationAnd average reactive power

Step 3, obtaining the average active power according to the step 2And active power instruction P given by microgrid inverter_refGiven angular frequency command omega of micro-grid inverter_refObtaining angular frequency omega of the virtual synchronous generator through a power angle control equation, and integrating the angular frequency omega to obtain a vector angle theta of the virtual synchronous generator;

step 4, according to the average reactive power obtained in the step 2Given reactive power instruction Q of microgrid inverter_refVoltage command U_refObtaining the terminal voltage U of the virtual synchronous machine through a reactive power control equation^*；

Step 5, firstly, according to the terminal voltage U obtained in the step 4^*And U obtained in step 1_cd,U_cqObtaining a capacitance current command signal by a voltage control equationThen according to the capacitor current command signalAnd component I of bridge arm side inductor current dq in step 1_ld,I_lqAnd a component I of the output current dq_od,I_oqObtaining the control signal U by a current control equation_d1,U_q1；

Step 6, according to the negative sequence component U of the capacitor voltage obtained in the step 1_CN-d,U_CN-qAnd the negative sequence component I of the inductor current_LN-d,I_LN-qObtaining a control signal U through a negative sequence voltage compensation control equation_d2,U_q2；

Step 7, the control signal U obtained in the step 5 and the step 6 is processed_d1,U_q1And U_d2,U_q2Respectively added to obtain control signals U_d,U_q；

Step 8, firstly according to the control signal U in the step 7_d,U_qAnd step 3, obtaining a three-phase bridge arm voltage control signal U through single synchronous rotation coordinate inverse transformation of the vector angle theta obtained in the step_a,U_b,U_cThen according to U_a,U_b,U_cAnd generating PWM control signals of the switching tubes of the inverter bridge of the microgrid inverter.

2. The virtual synchronous machine-based unbalance voltage compensation control method according to claim 1, wherein the active power calculation equation in the step 2 is

<math> <mrow> <mover> <mi>P</mi> <mo>&OverBar;</mo> </mover> <mo>=</mo> <mrow> <mo>(</mo> <munder> <mi>&Pi;</mi> <mi>h</mi> </munder> <mfrac> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <msup> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mn>2</mn> </msup> </mrow> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>2</mn> <mi>Q</mi> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mi>s</mi> <mo>+</mo> <msup> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <mfrac> <mn>1.5</mn> <mrow> <mi>&tau;s</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>U</mi> <mi>cq</mi> </msub> <msub> <mi>I</mi> <mi>oq</mi> </msub> <mo>+</mo> <msub> <mi>U</mi> <mi>cd</mi> </msub> <msub> <mi>I</mi> <mi>od</mi> </msub> <mo>)</mo> </mrow> <mo>,</mo> </mrow></math>

Wherein Q is the quality factor of the resonance controller, omega_hThe harmonic angular frequency to be filtered by the trap, s is the laplacian operator, and τ is the time constant of the first-order low-pass filter.

3. The virtual synchronous machine-based unbalance voltage compensation control method according to claim 1, wherein the reactive power calculation equation in the step 2 is as follows

<math> <mrow> <mover> <mi>Q</mi> <mo>&OverBar;</mo> </mover> <mo>=</mo> <mrow> <mo>(</mo> <munder> <mi>&Pi;</mi> <mi>h</mi> </munder> <mfrac> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <msup> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mn>2</mn> </msup> </mrow> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>2</mn> <mi>Q</mi> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mi>s</mi> <mo>+</mo> <msup> <msub> <mi>&omega;</mi> <mi>h</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>&CenterDot;</mo> <mfrac> <mn>1.5</mn> <mrow> <mi>&tau;s</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>U</mi> <mi>cd</mi> </msub> <msub> <mi>I</mi> <mi>oq</mi> </msub> <mo>-</mo> <msub> <mi>U</mi> <mi>cq</mi> </msub> <msub> <mi>I</mi> <mi>od</mi> </msub> <mo>)</mo> </mrow> <mo>,</mo> </mrow></math>

Wherein Q is the quality factor of the resonance controller, omega_hThe harmonic angular frequency to be filtered by the trap, s is the laplacian operator, and τ is the time constant of the first-order low-pass filter.

4. The virtual synchronous machine-based unbalanced voltage compensation control method of claim 1, wherein the power angle control equation in step 3 is

<math> <mrow> <mi>&omega;</mi> <mo>=</mo> <msub> <mi>&omega;</mi> <mi>ref</mi> </msub> <mo>+</mo> <mfrac> <mi>m</mi> <mrow> <mi>J</mi> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <mi>ms</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>ref</mi> </msub> <mo>-</mo> <mover> <mi>P</mi> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> <mo>,</mo> </mrow></math>

Wherein, ω is_refGiving an active power instruction P for the microgrid inverter_refThe nominal angular frequency of the time, m is a power angle control droop coefficient, J is a virtual moment of inertia time constant, omega of the simulation synchronous generator set₀The angular frequency is fixed for the grid.

5. The virtual synchronous machine-based unbalanced voltage compensation control method of claim 1, wherein the reactive power control equation in the step 4 is

<math> <mrow> <msup> <mi>U</mi> <mo>*</mo> </msup> <mo>=</mo> <msub> <mi>U</mi> <mi>ref</mi> </msub> <mo>+</mo> <mi>n</mi> <mrow> <mo>(</mo> <msub> <mi>Q</mi> <mi>ref</mi> </msub> <mo>-</mo> <mover> <mi>Q</mi> <mo>&OverBar;</mo> </mover> <mo>)</mo> </mrow> <mo>,</mo> </mrow></math>

Wherein, U_refGiving a reactive power instruction Q for a microgrid inverter_refAnd the voltage of the rated output capacitor and n are power angle control droop coefficients.

6. The virtual synchronous machine-based unbalance voltage compensation control method according to claim 1, wherein the voltage control equation in the step 5 is

<math> <mrow> <msubsup> <mi>I</mi> <mi>cd</mi> <mo>*</mo> </msubsup> <mo>=</mo> <msub> <mi>K</mi> <mi>p</mi> </msub> <mo>+</mo> <msub> <mi>K</mi> <mi>i</mi> </msub> <mo>/</mo> <mi>s</mi> <mo>+</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mi>r</mi> </msub> <mi>s</mi> </mrow> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>2</mn> <mi>Q</mi> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <mi>s</mi> <mo>+</mo> <msup> <mrow> <mo>(</mo> <mn>2</mn> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </mfrac> <mrow> <mo>(</mo> <msup> <mi>U</mi> <mo>*</mo> </msup> <mo>-</mo> <msub> <mi>U</mi> <mi>cd</mi> </msub> <mo>)</mo> </mrow> </mrow></math>，

<math> <mrow> <msubsup> <mi>I</mi> <mi>cq</mi> <mo>*</mo> </msubsup> <mo>=</mo> <msub> <mi>K</mi> <mi>p</mi> </msub> <mo>+</mo> <msub> <mi>K</mi> <mi>i</mi> </msub> <mo>/</mo> <mi>s</mi> <mo>+</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mi>r</mi> </msub> <mi>s</mi> </mrow> <mrow> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <mn>2</mn> <mi>Q</mi> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <mi>s</mi> <mo>+</mo> <msup> <mrow> <mo>(</mo> <mn>2</mn> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </mfrac> <mrow> <mo>(</mo> <mn>0</mn> <mo>-</mo> <msub> <mi>U</mi> <mi>cq</mi> </msub> <mo>)</mo> </mrow> </mrow></math>

Wherein, K_pIs a proportional control coefficient, K_iFor integral control coefficient, K_rIs the resonant controller scaling factor.

7. The virtual synchronous machine-based unbalance voltage compensation control method according to claim 1, wherein the current control equation in the step 5 is

$U_{d1}=K(I_{\mathrm{cd}}^{*}-I_{\mathrm{ld}}+I_{\mathrm{od}})$

$U_{q1}=K(I_{\mathrm{cq}}^{*}-I_{\mathrm{lq}}+I_{\mathrm{oq}}),$

Wherein K is a proportional control coefficient.

8. The virtual synchronous machine-based unbalance voltage compensation control method according to claim 1, wherein the negative sequence voltage compensation control equation in step 6 is

<math> <mrow> <msub> <mi>U</mi> <mrow> <mi>d</mi> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>-</mo> <msub> <mi>U</mi> <mrow> <mi>C</mi> <mo>_</mo> <mi>N</mi> <mo>-</mo> <mi>d</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>K</mi> <mn>2</mn> </msub> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <msub> <mi>LI</mi> <mrow> <mi>L</mi> <mo>_</mo> <mi>N</mi> <mo>-</mo> <mi>q</mi> </mrow> </msub> </mrow> <mrow> <mi>&tau;s</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> </mrow></math>，

<math> <mrow> <msub> <mi>U</mi> <mrow> <mi>q</mi> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mn>1</mn> </msub> <mrow> <mo>(</mo> <mn>0</mn> <mo>-</mo> <msub> <mi>U</mi> <mrow> <mi>C</mi> <mo>_</mo> <mi>N</mi> <mo>-</mo> <mi>q</mi> </mrow> </msub> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>K</mi> <mn>2</mn> </msub> <msub> <mi>&omega;</mi> <mn>0</mn> </msub> <msub> <mi>LI</mi> <mrow> <mi>L</mi> <mo>_</mo> <mi>N</mi> <mo>-</mo> <mi>d</mi> </mrow> </msub> </mrow> <mrow> <mi>&tau;s</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> </mrow></math>

Wherein, K₁For compensating the coefficient, K, for the voltage₂The current compensation coefficient is, L is a bridge side inductance value of the microgrid inverter, and tau is a filtering time constant.