Impedance Model for Instability Analysis of LCC-HVDCs Considering Transformer Saturation  

作　　者：Qin Jiang Ruiting Xu Baohong Li Xiang Chen Yue Yin Tianqi Liu Frede Blaabjerg 

机构地区：[1]College of Electrical Engineering,Sichuan University,Chengdu 610065,China [2]Smart Grid Key Laboratory of Sichuan Province,Chengdu 610065,China [3]Department of Energy Technology,Aalborg University,Aalborg 9920,Denmark

出　　处：《Journal of Modern Power Systems and Clean Energy》2024年第4期1309-1319,共11页现代电力系统与清洁能源学报（英文）

摘　　要：In line commutated converter based high-voltage direct current(LCC-HVDC)transmission systems,the transformer saturation can induce harmonic instability,which poses a serious threat to the safe operation of the power system.However,the nonlinear characteristics of the power grids introduced by the transformer saturation considerably limit the application of the conventional analysis methods.To address the issue,this paper derives a linear model for the transformer saturation caused by the DC current due to the converter modulation.Afterwards,the nonlinear characteristics of power grids with the transformer saturation is described by a complex valued impedance matrix.Based on the derived impedance matrix,the system harmonic stability is analyzed and the mechanism of the transformer saturation induced harmonic instability is revealed.Finally,the sensitivity analysis is conducted to find the key factors that influence the system core saturation instability.The proposed impedance model is verified by the electromagnetic transient simulation,and the simulation results corroborate the effectiveness of the proposed impedance model.Index TermsLine commutated converter based high voltage direct current(LCC-HVDC),transformer saturation,harmonic instability,impedance model.

关 键 词：Line commutated converter based high voltage direct current(LCC-HVDC) transformer saturation harmonic instability impedance model 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM41