基于序阻抗的虚拟同步发电机并网稳定性分析及虚拟阻抗设计  

Stability Analysis and Virtual Impedance Design of Virtual Synchronous Machine Based on Sequence Impedance

作　　者：刘欣[1] 郭志博 贾焦心 王利桐 Liu Xin;Guo Zhibo;Jia Jiaoxin;Wang Litong(Department of Electrical Engineering North China Electric Power University,Baoding 071003,China)

机构地区：[1]华北电力大学电力工程系,保定071003

出　　处：《电工技术学报》2023年第15期4130-4146,共17页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(52207102)。

摘　　要：在分布式发电高渗透率的微电网中,虚拟同步发电机(VSG)因可提供必要的频率和电压支撑而被广泛关注,其并网稳定性研究已成为热点问题。该文首先在获得VSG输出序阻抗矩阵的基础上,通过建立单输入单输出(SISO)等效模型,并结合Nyquist准则对VSG进行并网稳定性分析;然后,针对正负序之间存在的频率耦合现象,基于所建SISO等效序阻抗模型,对比分析了考虑频率耦合效应前后的VSG输出阻抗特性,揭示了频率耦合效应对VSG并网稳定性的影响机理,以及造成VSG并入强电网失稳的根本原因;最后,在上述机理分析的基础上,提出一种用于提升系统稳定性的虚拟阻抗简化设计方法,该方法从提升系统的幅值裕度的角度出发,直接利用SISO等效输出阻抗与电网阻抗二者的交互关系实现虚拟阻抗的定量计算,简化了虚拟阻抗的设计过程。仿真结果验证了稳定性分析的正确性以及虚拟阻抗设计方法的有效性。In microgrid with high penetration of distributed generation,the generalized Nyquist criterion based on return rate matrix or return difference matrix is often used to analyse the grid-connection stability of virtual synchronous generator(VSG),but the calculation process is complicated.Besides,existing studies have not identified the root cause of the instability of VSG's integration into the strong grid,and the mechanism analysis of the influence of frequency coupling effect on the output impedance characteristics of VSG remains to be deepened.In terms of stability improvement,existing virtual impedance design methods do not take full advantage of the characteristics of VSG output impedance and its interaction with the grid impedance,and there is still room for further simplification.Therefore,this paper conducts a comprehensive and systematic research on the mechanism analysis of microgrid VSG grid-connection stability and the design method of virtual impedance.Firstly,on the basis of obtaining VSG output sequence impedance matrix,this paper analyses the grid-connection stability of VSG by establishing single input single output(SISO)equivalent model and combining with Nyquist criterion.Secondly,based on the established SISO equivalent sequence impedance model,the influence mechanism of frequency coupling effect on the output impedance characteristics of VSG and the root cause of the instability of VSG's integration into the strong grid are compared and analysed.Finally,based on the above mechanism analysis,this paper proposes a virtual impedance simplified design method to improve system stability,from the perspective of improving the amplitude margin of the system,this method directly uses the interaction relationship between SISO equivalent output impedance and grid impedance to realize the quantitative calculation of virtual impedance,which simplifies the design process of virtual impedance.The results are as follows:first,the stability analysis method based on SISO equivalent sequence impedance model can e

关 键 词：虚拟同步发电机 SISO等效序阻抗模型 频率耦合效应 稳定性分析 虚拟阻抗设计 

分 类 号：TM712[电气工程—电力系统及自动化]