轻型直流输电系统的不对称故障控制策略  

Control Strategy for VSC-HVDC Transmission System During Unbalanced Fault

作　　者：邵文君[1] 宋强[1] 刘文华[1] 

机构地区：[1]清华大学电机工程与应用电子技术系,北京市海淀区100084

出　　处：《电网技术》2009年第12期42-48,共7页Power System Technology

摘　　要：基于电压源变流器(voltage source converter,VSC)的轻型直流输电(VSC-HVDC)正成为一种经济灵活的新型输电方式。但是当交流系统发生不对称故障时,系统中存在的负序分量在脉宽调制(pulse width modulation,PWM)的作用下会产生大量的非特征谐波,并严重恶化VSC-HVDC系统的控制性能。文章在换流站正序模型的基础上建立了系统的负序模型,提出一种基于精确反馈线性化理论的正负序电流非线性控制器,并针对系统故障时出现的直流过电压问题设计了2种应对策略。在电磁暂态仿真软件PSCAD/EMTDC下对上述控制策略进行了仿真验证,达到了预期的控制效果。The VSC-HVDC transmission system based on voltage source converter is becoming a new way for flexible power transmission due to its high controllability and high response speed. However, when unbalanced fault occurs in the AC system, negative-sequence components existing in AC system will lead to a lot of non-characteristic harmonics under the action of pulse width modulation （PWM）, so the control performance of VSC-HVDC system will be deteriorated. On the basis of the positive-sequence model of converter station, a negative-sequence model of VSC-HVDC system is built and a nonlinear controller for positive- and negative-sequence currents based on exact feedback linearization theory is proposed, and two coping strategies are designed according to the DC side overvoltage which occurs during system fault. The proposed control strategy is validated by electromagnetic transient simulation software PSCAD/EMTDC, and prospective control effect is achieved.

关 键 词：电压源变流器(VSC) 轻型直流输电 不对称故障 精确反馈线性化 负序电流控制 

分 类 号：TM721[电气工程—电力系统及自动化]