高压直流输电系统换相失败判断标准的仿真分析

对2008年南方电网交直流混联输电系统建立了详细的电磁暂态模型，通过对贵广I、贵广II、北郊、惠州4条直流输电系统换相失败的仿真研究发现，当电压降落到75%时并不一定发生换相失败，因此提出了换相失败的标准：电压降落到70%时也不一定发生换相失败，关键应看阀关断角是否小于阀去游离时间对应的最小角度、阀电压是否连续为零、阀电流是否连续；若是，则会发生换相失败，若不是，则不会发生换相失败。

Simulation Analysis on Commutation Failure Criteria for HVDC Transmission Systems

A detailed electromagnetic transient model for AC/DC hybrid power transmission system of China Southern Power Grid in the year of 2008 is established.By means of the simulation on commutaton failures occurred in converter stations,which belong to four DC transmission lines respectively,i.e.,three DC transmission lines from Guizhou province to Guangdong province and one DC transmission line from Three Gorges power station to Guangdong province,it is found that the commutation failure will not always occur while the voltage drops to 75% of its rated value.Thus the authors propose a criteria for commutation failure:the commutation failure will not always occur while the voltage drops to 70% of its rated value,the crux of the matter depends on that whether the margin angle of valve is smaller than the minimum angle corresponding to the free time of the valve,the voltage of valve is continuously zero and the current of the valve is continuous. When these conditions are ture,the commutation failure occurs; when these conditiona are false,the commutation failure will not occur.