摘要
基于模块化多电平换流器的高压直流(MMC-HVDC)输电系统的链路延时可能会引发系统产生高频振荡。文中通过Pade近似对延时环节进行等值,建立了基于四阶Pade近似等值延时环节的MMC-HVDC系统的状态空间模型。通过在阶跃工况下与PSCAD/EMTDC中详细电磁暂态模型动态特性的对比以及高频振荡的复现,验证了所建立的状态空间模型的正确性及四阶Pade近似等值延时环节的有效性。然后,研究了延时环节时间常数对系统特征根及高频振荡特性的影响,结果表明,基于特征值分析法对所建立的考虑延时环节特性的MMC-HVDC系统状态空间模型进行分析,可以得到引发系统高频振荡的临界延时时间。最后,通过参与因子分析法探究了引起系统发生高频振荡的主要因素,结果表明,系统的高频振荡现象主要是由交流系统特性与含有延时环节的MMC-HVDC系统特性之间的耦合作用引起。
The circuit time delay of modular multilevel converter based high voltage direct current(MMC-HVDC)transmission systems may cause high-frequency oscillation of power systems.This paper establishes an equivalent model of the time-delay link based on the Pade approximation,and develops a state space model of MMC-HVDC system by equivalently representing the timedelay based on the fourth-order Pade approximation.By comparing the dynamic characteristics of the model with those of the detailed electromagnetic transient model in PSCAD/EMTDC under the step condition and the recurrence of high-frequency oscillation,the correctness of the developed state space model and the validity of the fourth-order Pade approximation for the timedelay equivalent are verified.Then,the influence of the time constant of the time-delay on the system eigenvalues and the highfrequency oscillation characteristics is studied.The results show that,based on the eigenvalue analysis method,the critical delay time that causes the system high-frequency oscillation can be obtained by analyzing the state space model of MMC-HVDC system considering the delay link characteristics.Finally,based on participation factor analysis method,the main factors that cause the system high-frequency oscillation are studied.The results show that the system high-frequency oscillation is mainly caused by the coupling between the characteristics of AC system and MMC-HVDC system with the time-delay link.
作者
郭春义
彭意
徐李清
杨硕
胡应宏
GUO Chunyi;PENG Yi;XU Liqing;YANG Shuo;HU Yinghong(School of Electrical and Electronic Engineering,North China Electric Power University,Beijing 102206,China;Electric Power Research Institute of State Grid Jibei Electric Power Co.,Ltd.,Beijing 100045,China;North China Electric Power Research Institute Co.,Ltd.,Beijing 100045,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2020年第22期119-126,共8页
Automation of Electric Power Systems
基金
国家电网有限公司科技项目(柔直电网模块化电压源换流阀高次谐波机理与抑制措施,5500-202014057A-0-0-00)。
关键词
柔性直流输电
模块化多电平换流器
高频振荡
延时环节
状态空间模型
特征值分析法
flexible DC transmission
modular multilevel converter(MMC)
high-frequency oscillation
time-delay link
state space model
eigenvalue analysis method
