摘要
分析了高压直流(HVCD)换相失败的机理及发生换相失败的原因,介绍了三?广直流输电工程换相失败预测控制模块,针对其中u0检测在交流电压过零时故障启动慢和abc-αβ坐标变换在三相故障时不能有效地预防换相失败的问题,提出了一种基于sin-cos分量检测的改进方法,并利用PSCAD/EMTDC软件建立了双馈入直流系统模型,该方法将单相交流电压分解为两个以基波频率旋转的分量,可快速地判断交流系统故障,一旦检测到故障,立即减小触发角,从而增加换相裕度,避免换相失败的发生。仿真结果表明:该方法能够在单相接地故障和三相故障时有效地减少多馈入直流系统发生换相失败的几率。
The mechanism of commutation failure of DC-AC converter was studied and the theory of commutation failure prediction control module of Three Gorges-Guangdong HVDC system was analysed. The u0 detector of CFPREV acts very slowly upon crossing zero of AC voltage and under the condition of three-phase faults abc-αβ transformation detection has very limited improvement of commutation failure, a new method based on an idea of sin-cos components detector is presented to mitigate commutation failure in multi-infeed HVDC systems.This method predicts quickly ac faults in terms of two components on the rotational reference frame synchronized with the ac system frequency. After detecting the fault, an additional angle is deduced from the firing order at the inverter station, which in practice enlarges the commutation margin. A dual-infeed HVDC model based on PSCAD/EMTDC is built and the simulation results show that it is very effective in reducing the probability of commutation failure in MIDC.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2005年第14期1-6,共6页
Proceedings of the CSEE