摘要
针对光伏虚拟同步发电机(virtual synchronous generators,VSG)经高压直流输电(modular multilevel converter based high voltage direct current,MMC-HVDC)送出系统所存在的次同步振荡(subsynchronous oscillation,SSO)风险,建立系统线性化数学模型。提出一种改进型虚拟同步控制策略,利用特征值法分析当功率发生扰动时,光伏虚拟同步发电系统有功控制环节、无功控制环节、虚拟电感、MMC-HVDC桥臂电感、电流矢量控制环节对系统SSO的阻尼特性和频率特性均会产生影响,并在PSCAD/EMTDC仿真平台进行验证。结果表明:引入VSG控制后,在外送系统中发生功率扰动的过程中,存在光伏VSG和MMC-HVDC共同参与的次同步振荡模式;在光伏VSG侧,有功调频系数Kf过大或虚拟电感Lv过小均会导致系统失稳;MMC-HVDC侧,电压环积分系数Ki4增大会导致系统失稳,而增大桥臂电感Lg会增强系统稳定性。
To address the issue of subsynchronous oscillation(SSO)arising when photovoltaic virtual synchronous generators(VSG_PV)transmit power through modular multi-level converter-based high-voltage direct current(MMC-HVDC)systems,a linearized mathematical model of the system is developed.An improved virtual synchronous control strategy is proposed.Using the eigenvalue analysis method,the study reveals that,under power disturbances,several factors-including the active and reactive control links,virtual inductance,MMC-HVDC bridge arm inductance,and current vector control loop-significantly affect the damping and frequency characteristics of SSO in the VSG-PV system.These findings are validated through simulation on the PSCAD/EMTDC platform.Results show that the integration of the VSG function introduces a sub-synchronous oscillation mode in which both the photovoltaic VSG and MMC-HVDC participate during power disturbances in the outgoing system.On the VSG side,an excessively large active frequency modulation coefficient Kf or a too-small virtual inductance Lv can lead to system instability;on the MMC-HVDC side,increasing the integral coefficient of the voltage loop Ki4 may induce system instability,whereas increasing the bridge arm inductance Lg enhances system stability.
作者
刘国庆
李彦哲
刘源涛
王颖
LIU Guoqing;LI Yanzhe;LIU Yuantao;WANG Ying(School of Automation&Electrical Engineering,Lanzhou Jiaotong University,Lanzhou 730070,P.R.China;Pingdingshan Yao Meng Power Generation Co.,Ltd.,Pingdingshan,Henan 467031,P.R.China)
出处
《重庆大学学报》
北大核心
2025年第9期21-36,共16页
Journal of Chongqing University
关键词
虚拟同步发电机
MMC-HVDC
次同步振荡
小信号分析
virtual synchronous generators
MMC-HVDC
subsynchronous oscillation(SSO)
small signal analysis
作者简介
刘国庆(1999—),男,硕士研究生,主要从事电力系统稳定性研究,(E-mail)18219617712@163.com。;通信作者:李彦哲,女,教授,(E-mail)2524225367@qq.com。
