云广直流工程换流器交流侧接地故障仿真分析

云广直流输电工程采用双12脉动换流器串联的特殊结构，其换流器发生故障时的运行特性有待研究。基于云广直流输电工程控制保护系统的RTDS仿真实验数据，研究了站间通信处于正常和故障两种状态下的换流阀的交流侧接地故障，发现故障电流由于周期性的两相短路和三相短路从而形成周期性变化，建议增加直流极差动87DCM保护动作延时以避免保护动作可能扩大停电范围。

Simulation Analysis of the Grounding Fault of Converter's AC Site in Yunnan-Guangong DC Transmission Project

As the constructure of two 12-pulse converters in series adopted in Yunnan-Guangdong DC transmission project is so special that its operational characteristics in the convertors failure is to be studied. Based on the RTDS data of the project's control and protection system, this paper analyzes the ground fault performance on the converter's AC site in the cases of inter-substation communication being both normal and in failure, pointing out that the fault current is in periodical change due to the cyclical two-phases ground fault and three-phases ground fault, and proposing to increase the delayed time of the pole DC differential protection so to prevent a larger shutdown range caused by the DC protection action.