摘要
换流站内发生的交流系统故障会对交直流系统产生严重的危害。通过对换流阀换相电压的特性分析指出:站内发生交流接地时会伴随桥臂短路及交流系统复故障的出现;相间故障则表现为不平衡换相。通过接地故障发生后换流阀的电流时间函数来说明故障电流呈现交流多相短路的特征。通过故障等效交流电路来研究交直流保护特性,并得出结论:对于接地故障,电流互感器(current transformer,CT)安装在不同位置时,阀短路保护、桥差保护均能正确动作;但发生相间故障时,却会造成某些工况下保护不能动作;在连接高端阀的交流系统接地时交流保护的距离元件有时会有超越现象。最后提出采用零序补偿分量的方法来提高启动元件的性能。CIGRE高压直流(high voltage direct current,HVDC)模型验证了分析结论。
It may cause severe damages to the AC and DC systems when the faults in the AC system of converter station occur. By analyzing the characteristics of the valve commutating voltage, it can be concluded that the ground fault at the converter station will cause short circuit across the bridges and multiple complex AC faults, and the line-to-line fault will result in unbalanced commutation. The fault current is characterized as AC short circuit among multiple phases and this can be illustrated by the time function of the commutating valve current after ground fault taking place. The paper analyzes AC and DC protections by the equivalent model of the AC fault circuit. It shows that for ground faults, the valve short circuit protection and bridge differential protection can operate correctly with different current transformer （CT） locations. However, under some operating conditions, the protection system may fail to operate for line-to-line faults. In addition, sometimes the distance components of AC relay have overreach phenomenon when a AC ground fault at the high-voltage side of the valves occurs. Finally, a method using zero-sequence compensation component, which can improve the performance of the startup component, was proposed. Application to the CIGRE high voltage direct current （HVDC） benchmark model verified the analytical results.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2011年第22期88-95,共8页
Proceedings of the CSEE
关键词
电力系统
交流故障
高压直流
换流站
阀短路保护
桥差保护
power systems
AC fault
high voltage direct current （HVDC）
converter stations
valve short protections
bridge differential protections
