文章摘要
刘倪,张昌华,廖丽,等.计及无功电压环节的VSG虚拟转矩及振荡失稳机理分析[J].电力系统自动化,2019,43(6):107-115. DOI: 10.7500/AEPS20180608005.
LIU Ni,ZHANG Changhua,LIAO LI, et al.Analysis on Virtual Torque and Oscillation Instability Mechanism of Virtual Synchronous Generator with Reactive Power-Voltage Controller[J].Automation of Electric Power Systems,2019,43(6):107-115. DOI: 10.7500/AEPS20180608005.
计及无功电压环节的VSG虚拟转矩及振荡失稳机理分析
Analysis on Virtual Torque and Oscillation Instability Mechanism of Virtual Synchronous Generator with Reactive Power-Voltage Controller
DOI:10.7500/AEPS20180608005
关键词: 小信号模型  虚拟同步发电机  鲁棒下垂控制器  并网逆变器  虚拟转矩系数
KeyWords: small-signal model  virtual synchronous generator(VSG)  robust droop controller  grid-connected inverter  virtual torque coefficient
上网日期:2019-02-21
基金项目:中央高校基本科研业务费专项资金资助项目(ZYGX2015J104);国家自然科学基金资助项目(51677020)
作者单位E-mail
刘倪 电子科技大学机械与电气工程学院, 四川省成都市 611731  
张昌华 电子科技大学机械与电气工程学院, 四川省成都市 611731 zhangchanghua@uestc.edu.cn 
廖丽 电子科技大学机械与电气工程学院, 四川省成都市 611731  
陈昕 重庆邮电大学自动化学院, 重庆市 400065  
陈树恒 电子科技大学机械与电气工程学院, 四川省成都市 611731  
刘群英 电子科技大学机械与电气工程学院, 四川省成都市 611731  
摘要:
      通过模拟同步发电机的机电暂态过程,虚拟同步发电机(VSG)技术成为并网逆变器接入电网的一个颇具吸引力的方案。然而,VSG也存在功率振荡现象,相关机理的研究有待开展。文中借鉴传统电力系统中的转矩分析理论,建立了计及无功电压环节的VSG小信号模型,并结合振荡模态,重新定义了虚拟转矩系数。然后,通过分析该系数与稳定性之间的关系,从数学上证明虚拟阻尼转矩不足将导致VSG出现功率振荡失稳。之后,以鲁棒下垂控制的VSG为例,给出了虚拟转矩系数的计算方法,并在PSCAD/EMTDC和VSG实验平台验证了该结论的正确性。最后,从系统初始状态、线路参数及控制器参数等多个角度出发,讨论了VSG无功电压环节对虚拟转矩系数及系统小信号稳定性的影响,可为VSG控制器设计和系统小信号稳定性分析提供依据。
Abstract:
      Virtual synchronous generator(VSG)has become an attractive scheme for connecting inverters with grids by simulating electromechanical transient process of synchronous generators. However, there also exists power oscillation problems in the VSG, and the related research on oscillation mechanism is needed. Based on the theory of torque analysis in the traditional power system, this paper establishes a small-signal model of VSG with reactive power-voltage controller. Combined with the oscillation mode, the virtual torque coefficient is redefined. Then the relationship between the virtual torque coefficient and VSG stability is analyzed. It is mathematically proved that the lack of virtual damping torque will lead to power oscillation instability of VSG. Taking the VSG with robust droop control as an example, the calculation method of virtual torque coefficient is given, and the conclusion is verified through PSCAD/EMTDC simulation and physical experiment. Finally, this paper discusses the effect of VSG with reactive power-voltage controller on the virtual torque coefficient and system small-signal stability from different perspectives, such as the initial state of the system, line parameters and controller parameters. The research is beneficial to the VSG controller design and the system small-signal stability analysis.
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