含串补及STATCOM的交直流系统稳定性分析及改善方法  

Stability Analysis and Improvement Method for AC/DC System with Series Compensation and STATCOMs

作　　者：夏海涛 周小平[1] 刘一锋 洪乐荣 罗安[1] XIA Haitao;ZHOU Xiaoping;LIU Yifeng;HONG Lerong;LUO An(National Electric Power Conversion and Control Engineering Technology Research Center(Hunan University),Changsha 410082,China)

机构地区：[1]国家电能变换与控制工程技术研究中心(湖南大学),湖南省长沙市410082

出　　处：《电力系统自动化》2022年第22期151-162,共12页Automation of Electric Power Systems

基　　金：湖南省自然科学基金资助项目(2020JJ5081);国家自然科学基金资助项目(51907058)。

摘　　要：研究了受端交直流系统中由串补及静止同步补偿器(STATCOM)引发的小信号失稳问题。基于系统闭环传递函数的主导极点轨迹的变化规律,分析了串补电容、STATCOM及其并联数量对高压直流输电系统小信号稳定性的影响。理论结果表明:投入串补有利于系统低频和高频稳定性但会使系统增加一对中频极点,而该中频极点会降低系统整体的稳定裕度;投入STATCOM能增强系统中频阻尼,但随着其并联台数的增加,系统高频阻尼将会变弱。针对这一现象,从定关断角控制特性和频域阻抗(导纳)特性2个角度给出了相应的机理解释。为了改善系统中高频稳定性,提出了触发角指令反馈控制及有功电流补偿控制。然后,利用PSCAD/EMTDC仿真软件验证了上述理论分析结果的正确性及所提方法的有效性。最后,比较了逆变站分别采用定关断角控制和电压控制这2种情形下系统的稳定性差异。The small-signal instability problem of the receiving end of the AC/DC system caused by series compensation(SC)and multiple static synchronous compensators(STATCOMs)is studied.Based on the change law of the dominant pole trajectories of the system closed-loop transfer function,the impacts of SC capacitor,STATCOM and its parallel number on the small-signal stability of the high voltage direct current(HVDC)transmission system are analyzed.The theoretical results reveal that:the application of SC is beneficial to the system stability at low and high frequencies,but it adds a pair of mid-frequency poles to the system,and the mid-frequency poles reduce the overall stability margin of the system;the application of STATCOM strengthens the system damping at the mid-frequency,but the system stability at the high frequency becomes worse with more STATCOMs in parallel.Aiming at the phenomenon,the corresponding mechanism explanations are given from the perspectives of the characteristics of constant extinction angle control and frequency-domain impedance(admittance).In order to improve the mid-and high-frequency stability of the system,the firing angle order feedback control and the active current compensation control are proposed.Then,the validity of the theoretical analysis results and the effectiveness of the proposed methods are verified by the PSCAD/EMTDC simulation software.Finally,the stability difference of the system is compared when the inverter adopts the constant extinction angle control and the constant voltage control.

关 键 词：高压直流输电 电网换相换流器 串补 静止同步补偿器 小信号稳定性 控制灵敏度指标 稳定性分析 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM761.12