Dynamic Power Decoupling Control of Virtual Synchronous Generator Based on Improved Virtual Impedance

doi:10.12096/j.2096-4528.pgt.23172

Abstract

Abstract:

Objectives When a virtual synchronous generator (VSG) is connected to a medium and low voltage distribution network, the line impedance exhibits resistive and inductive characteristics, resulting in strong coupling in the VSG output power. This coupling can cause power oscillations and even deviations in the internal power control, affecting power quality and transmission stability. To address these issues, an improved power decoupling strategy based on virtual capacitance is proposed. Methods By simplifying the VSG grid-connected model and conducting small-signal modeling, the power coupling mechanism is analyzed to identify key factors contributing to coupling. Based on this analysis, the concept of virtual capacitance is introduced, and an improved control method utilizing virtual capacitance is proposed. Finally, simulations are conducted on the MATLAB/Simulink platform to verify the effectiveness of the proposed strategy. Results The capacitive characteristics of virtual capacitance not only enhance the system’s operational stability, but also correct the output voltage reference, effectively mitigating oscillations exacerbated by power coupling. Conclusions The proposed control strategy reduces the interference caused by active power command changes or load switching on reactive power, suppressing strong power coupling during the dynamic process of the system.

Key words: virtual synchronous generator (VSG), power coupling, virtual capacitance, microgrid, line impedance, virtual impedance, power decoupling, distributed energy resources

CLC Number:

TK 01

Mingwei REN, Cong SHAO, Kai SHI, Peifeng XU, Yuxin SUN. Dynamic Power Decoupling Control of Virtual Synchronous Generator Based on Improved Virtual Impedance[J]. Power Generation Technology, 2025, 46(4): 797-806.

Figures/Tables 18

Fig. 1 Block diagram of VSG basic control

Fig. 2 Control structure of VSG

Fig. 3 Equivalent circuit of VSG connected to AC power grid

Fig. 4 Small-signal model of the power loop

Fig. 5 Grid-connected VSG system with virtual impedance

Fig. 6 Dual closed-loop control diagram of voltage and current with virtual impedance

Fig. 7 Schematic diagram of power coupling principle

Fig. 8 Grid-connected VSG system with virtual capacitance

Fig. 9 Control block diagram with improved virtual impedance

Tab. 1 Main parameters of VSG main circuits and control loops

参数	数值
u_dc/V	800
ω_N	314.2
R₁/Ω	0.2
L₁/mH	5
R/Ω	20
R_l/Ω	1
X_l/mH	0.2
J/(kg⋅m²)	0.058
D_p /(N⋅m)	5
K_p1	6.5
K_p2	1.2
D_q	320
C_v/F	0. 8
L_v/mH	4
开关频率f_s/kHz	10

Fig. 10 Effects of virtual inductance and virtual capacitance on output impedance

Fig. 11 Active power output under different virtual inductance

Fig. 12 Active power output under different virtual capacitance

Fig. 13 Output power without virtual impedance

Fig. 14 Output power with the improved decoupling strategy

Fig. 15 Voltage and current on the grid side without virtual impedance

Fig. 16 Voltage and current on the grid side with improved decoupling strategy

Fig. 17 Output power under different control strategies

References 25

[1]	李小双，冷亚军，吴坚．基于多目标投影寻踪模型的电力发展水平评价方法[J]．电力科学与技术学报，2024，39(5)：46-57．
	LI X S， LENG Y J， WU J ．Evaluating method for power development level based on multi-objective projection pursuit model[J]．Journal of Electric Power Science and Technology，2024，39(5)：46-57．
[2]	LI D D， ZHU Q W， LIN S F，et al ．A self-adaptive inertia and damping combination control of VSG to support frequency stability[J]．IEEE Transactions on Energy Conversion，2017，32(1)：397-398． doi:10.1109/tec.2016.2623982
[3]	张玮，白恺，鲁宗相，等．特大型新能源基地面临挑战及未来形态演化分析[J]．全球能源互联网，2023，6(1)：10-25．
	ZHANG W， BAI K， LU Z X，et al ．Analysis of the challenges and future morphological evolution of super large-scale renewable energy base[J]．Journal of Global Energy Interconnection，2023，6(1)：10-25．
[4]	杨继鑫，王久和，王勉，等．基于无源控制的光储直流微网虚拟惯性控制策略研究[J]．发电技术，2021，42(5)：576-584． doi:10.12096/j.2096-4528.pgt.20080
	YANG J X， WANG J H， WANG M，et al ．Research on virtual inertial control strategy of DC microgrid with photovoltaic and storage system based on passivity-based control[J]．Power Generation Technology，2021，42(5)：576-584． doi:10.12096/j.2096-4528.pgt.20080
[5]	黎静华，朱振铎，兰飞．基于协同控制理论的微电网频率控制[J]．电力建设，2023，44(3)：113-121．
	LI J H， ZHU Z D， LAN F ．Microgrid frequency control based on cooperative control theory[J]．Electric Power Construction，2023，44(3)：113-121．
[6]	朱子民，张锦芳，常清，等．大规模新能源接入弱同步支撑柔直系统的送端自适应VSG控制策略[J]．中国电力，2024，57(5)：211-221．
	ZHU Z M， ZHANG J F， CHANG Q，et al ．Adaptive VSG control strategy of sending end for large-scale renewable energy connected to weakly-synchronized support VSC-HVDC system[J]．Electric Power，2024，57(5)：211-221．
[7]	SHINTAI T， MIURA Y，ISE T ．Oscillation damping of a distributed generator using a virtual synchronous generator[J]．IEEE Transactions on Power Delivery，2014，29(2)：668-676． doi:10.1109/tpwrd.2013.2281359
[8]	李琳，张晓楠，李庚银，等．考虑内外环交互作用的VSG并网振荡特性[J]．电力建设，2024，45(4)：66-76．
	LI L， ZHANG X N， LI G Y，et al ．Characteristics of VSG grid-connected system oscillation considering the interaction between inner and outer loops[J]．Electric Power Construction，2024，45(4)：66-76．
[9]	刘建伟，李学斌，刘晓鸥．有源配电网中分布式电源接入与储能配置[J]．发电技术，2022，43(3)：476-484． doi:10.12096/j.2096-4528.pgt.21068
	LIU J W， LI X B， LIU X O ．Distributed power access and energy storage configuration in active distribution network[J]．Power Generation Technology，2022，43(3)：476-484． doi:10.12096/j.2096-4528.pgt.21068
[10]	闫来清，邓熙炜，赵喆，等．基于自适应前馈补偿的VSG功率解耦控制策略[J]．电力系统保护与控制，2024，52(24)：64-73．
	YAN L Q， DENG X W， ZHAO Z，et al ．VSG power decoupling control strategy based on adaptive feedforward compensation[J]．Power System Protection and Control，2024，52(24)：64-73．
[11]	黄萌，舒思睿，李锡林，等．面向同步稳定性的电力电子并网变流器分析与控制研究综述[J]．电工技术学报，2024，39(19)：5978-5994．
	HUANG M， SHU S R， LI X L，et al ．A review of synchronization-stability-oriented analysis and control of power electronic grid-connected converters[J]．Transactions of China Electrotechnical Society，2024，39(19)：5978-5994．
[12]	周贤正，荣飞，吕志鹏，等．低压微电网采用坐标旋转的虚拟功率V/f下垂控制策略[J]．电力系统自动化，2012，36(2)：47-51．
	ZHOU X Z， RONG F， LV Z P，et al ．A coordinate rotational transformation based virtual power V/f droop control method for low voltage microgrid[J]．Automation of Electric Power Systems，2012，36(2)：47-51．
[13]	颜湘武，王月茹，王星海．基于坐标变换的微网功率解耦及限幅控制策略[J]．湖南大学学报(自然科学版)，2016，43(8)：85-91．
	YAN X W， WANG Y R， WANG X H ．A coordinate transformation based power decoupling and restriction control strategy for microgrid[J]．Journal of Hunan University (Natural Sciences)，2016，43(8)：85-91．
[14]	宋兴龙，杨旭红，陈昊．基于单一旋转角虚拟功率的虚拟同步发电机功率解耦策略[J]．上海电力大学学报，2020，36(6)：529-534．
	SONG X L， YANG X H， CHEN H ．Virtual synchronous generator power decoupling strategy based on virtual power of single rotion angle[J]．Journal of Shanghai University of Electric Power，2020，36(6)：529-534．
[15]	朱慧敏，苑舜．基于功率解耦控制的虚拟同步发电机功率振荡抑制策略[J]．智慧电力，2020，48(4)：70-76． doi:10.1553/isr_fb048s70
	ZHU H M， YUAN S ．Power oscillation suppression strategy of virtual synchronous generator based on power decoupling control[J]．Smart Power，2020，. doi:10.1553/isr_fb048s70 48(4)：70-76． doi:10.1553/isr_fb048s70
[16]	李威，马美玲，孙伟卿．考虑功率耦合的构网型多VSG系统频率振荡特性分析[J]．电力工程技术，2025，44(2)：44-54．
	LI W， MA M L， SUN W Q ．Analysis of frequency oscillation characteristics in grid-forming multi-VSG systems considering power coupling[J]．Electric Power Engineering Technology，2025，44(2)：44-54．
[17]	倪亮，刘桂英，苏乾坤，等．孤岛微网VSG并联系统环流抑制策略[J]．电测与仪表，2025，62(4)：122-129．
	NI L， LIU G Y， SU Q K，et al ．Circulating current suppression strategy for VSG parallel system with island microgrid[J]．Electrical Measurement & Instrumentation，2025，62(4)：122-129．
[18]	DONG N B， LI M F， CHANG X F，et al ．Robust power decoupling based on feedforward decoupling and extended state observers for virtual synchronous generator in weak grid[J]．IEEE Journal of Emerging and Selected Topics in Power Electronics，2023，11(1)：576-587． doi:10.1109/jestpe.2022.3207973
[19]	HU Y F， SHAO Y T， YANG R C，et al ．A configurable virtual impedance method for grid-connected virtual synchronous generator to improve the quality of output current[J]．IEEE Journal of Emerging and Selected Topics in Power Electronics，2020，8(3)：2404-2419． doi:10.1109/jestpe.2019.2918386
[20]	LI M X， WANG Y， LIU Y H，et al ．Enhanced power decoupling strategy for virtual synchronous generator[J]．IEEE Access，2020，8：73601-73613． doi:10.1109/access.2020.2987808
[21]	张平，石健将，李荣贵，等．低压微网逆变器的“虚拟负阻抗”控制策略[J]．中国电机工程学报，2014，34(12)：1844-1852．
	ZHANG P， SHI J J， LI R G，et al ．A control strategy of “virtual negative” impedance for inverters in low-voltage microgrid[J]．Proceedings of the CSEE，2014，34(12)：1844-1852．
[22]	颜湘武，崔森，贾焦心．虚拟稳态同步负阻抗的VSG功率解耦策略[J]．电力系统保护与控制，2020，48(18)：102-113．
	YAN X W， CUI S， JIA J X ．Virtual steady state synchronous negative impedance of a VSG power decoupling strategy[J]．Power System Protection and Control，2020，48(18)：102-113．
[23]	RATHNAYAKE D B， BAHRANI B ．Multivariable control design for grid-forming inverters with decoupled active and reactive power loops[J]．IEEE Transactions on Power Electronics，2023，38(2)：1635-1649． doi:10.1109/tpel.2022.3213692
[24]	WEN T L， ZHU D H， ZOU X D，et al ．Power coupling mechanism analysis and improved decoupling control for virtual synchronous generator[J]．IEEE Transactions on Power Electronics，2021，36(3)：3028-3041． doi:10.1109/tpel.2020.3017254
[25]	戚军，李袁超，童辉，等．基于动态虚拟电流前馈的预同步VSG功率二阶解耦策略[J]．电网技术，2020，44(9)：3556-3565．
	QI J， LI Y C， TONG H，et al ．Second-order power decoupling control in pre-synchronized VSG based on dynamic virtual current feedforward control[J]．Power System Technology，2020，44(9)：3556-3565．