基于虚拟同步发电机控制的并网逆变器切换型振荡及其非光滑分岔特性  

Switched Oscillation and Its Non-Smooth Bifurcation Characteristics in Grid-Connected Inverter Based on Virtual Synchronous Generator Control

作　　者：纪君奇 杨黎晖[1] 马西奎[1] Ji Junqi;Yang Lihui;Ma Xikui(School of Electrical Engineering Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学电气工程学院,西安710049

出　　处：《电工技术学报》2024年第24期7860-7873,共14页Transactions of China Electrotechnical Society

基　　金：国家能源集团科技创新项目(GJNY-21-89);国家重点研发计划项目(2021YFB2601300,2021YFB2601405)资助。

摘　　要：在大扰动下,基于虚拟同步发电机(VSG)控制的并网逆变器因限幅环节饱和发生的切换型振荡对电力系统的安全稳定运行构成威胁,其振荡机理和影响因素复杂。为此,该文研究大扰动下由VSG限幅环节饱和引发的切换型振荡的机理,并分析限幅环节的类型、限幅值大小和系统参数对切换型振荡特性的影响。首先,介绍切换型振荡和非光滑分岔理论,以及基于VSG控制的并网逆变器及其限幅环节;其次,分析大扰动下VSG并网逆变器切换型振荡现象,并基于相图法揭示其动力学本质是系统发生了非光滑分岔;再次,分析非光滑分岔与限幅环节的类型和限幅值大小的关系,指出非光滑分岔是由多个限幅环节共同作用引发的;最后,分析VSG控制参数和外部参数对系统非光滑分岔特性的影响。结果表明,限幅值越小和故障程度越严重,系统越容易发生切换型振荡。As a grid-forming inverter,the inverter based on virtual synchronous generator(VSG)control can contribute to the regulation of grid voltage and frequency.Power systems with a high penetration of new energy sources and power electronics are prone to stability when applied with VSG-controlled inverters.However,the switched oscillation induced by the saturation of limiters in the grid-connected inverter based on VSG control under large disturbances can threaten the stability of the power system.This paper studies the mechanism of such switched oscillations.The effects of limiter type,limiter value,and system parameters on the switched oscillation are also analyzed.Firstly,the switched oscillation and non-smooth bifurcation theory are introduced,as well as the VSG-controlled inverter and its limiters.Secondly,the switched oscillation in the VSG-controlled inverter under large disturbances is analyzed in terms of time-domain waveforms and amplitude-frequency characteristics,According to phase diagrams,the switched oscillation is essentially induced by the non-smooth bifurcation.Thirdly,the relationship between non-smooth bifurcation and limiter type and limiter value is analyzed.Non-smooth bifurcation is induced by the saturation of multiple limiters.Finally,the effects of VSG control parameters and external parameters on the non-smooth bifurcation characteristics are analyzed.The results show that the switched oscillation is more likely to occur with smaller limiter values and larger disturbances.Simulation results show that the power oscillation occurs in the VSG-controlled inverter with limiters under a symmetrical short-circuit fault with a dominant oscillation frequency of 0.36 Hz.The phase diagram during the power oscillation shows that a non-smooth limit cycle occurs,and the C-bifurcation essentially induces the switched oscillation according to the trajectory evolution.Non-smooth bifurcations may occur when both current and modulation signal limiters are included.In addition,as the parameter values are varied,

关 键 词：虚拟同步发电机 构网型控制 限幅 切换型振荡 非光滑分岔 

分 类 号：TM464[电气工程—电器] TM712