Impedance Modeling and Stability Analysis of a Three-phase Three-level NPC Inverter Connected to the Grid  

作　　者：Bo Zhang Xiong Du Jingbo Zhao Jiapei Zhou Xiaoming Zou 

机构地区：[1]State Key Laboratory of Power Transmission Equipment&System Security and New Technology(Chongqing University),Shapingba District,Chongqing 400044,China [2]Power System Technology Center,Electric Power Research Institute of State Grid,Jiangsu Electric Power Co.,Ltd.,Jiangsu 320115,China [3]HVDC Simulation Center,Department of HVDC technology,Global Energy Interconnection Research Institute,Beijing 102209,China

出　　处：《CSEE Journal of Power and Energy Systems》2020年第2期270-278,共9页中国电机工程学会电力与能源系统学报（英文）

基　　金：This work was supported in part by the National Natural Science Key Foundation of China under Grant 51937001;the Natural Science Foundation Key Project of Chongqing Province under Grant cstc2019jcyj-zdxmX0005;National Grid Project under Grant 5200-201958248A-0-0-00.

摘　　要：The interaction between grid-connected inverters and the grid may cause stability issues,and compromise the reliable operation of the inverters.This study investigates the stability of a three-level neutral point clamped(NPC)inverter connected to the grid using impedance-based methods.Because the impedance model of a three-phase three-level NPC inverter has not yet been reported,this study fills the literature gap by analyzing the influence of three-level DC-side neutral point control on the impedance characteristics.By fully considering the DC bus dynamics and DC voltage control loop,and the current loop and phase-locked loop(PLL),the admittance model of a three-phase three-level NPC inverter is established and verified by simulation.Additionally,in the stability analysis of a threelevel NPC inverter grid-connected system,the frequency coupling introduced by the PLL and DC bus dynamics is included with the help of an established admittance model.The stability of the grid-connected system under different grid short circuit ratios(SCR)and operating power levels is analyzed according to the Nyquist stability criterion.The experimental results revealed that the established impedance model of the three-phase three-level NPC inverter can properly represent the stability of this system.

关 键 词：Grid-connected inverter neutral point control STABILITY THREE-LEVEL 

分 类 号：TM46[电气工程—电器]