柔性直流输电系统桥臂过流保护定值配合方法

针对交流故障下柔性直流桥臂过流保护可能误动导致故障穿越失败，直流故障下桥臂过流保护拒动或慢动可能导致开关器件过流等问题，讨论了柔性直流换流阀桥臂过流保护功能在阀控和直流保护装置中的配置和定值配合关系。借鉴交流保护定值配合图的概念，提出了桥臂过流保护功能在阀控装置与直流保护装置中的优化配合方法。最后，在PSCAD/EMTDC中搭建了仿真平台，结果表明所述桥臂过流保护配合关系和定值设置方法可在交流故障下成功实现故障穿越，并可在直流极间短路等严重故障下可靠闭锁换流器并触发旁路晶闸管，降低电力电子器件的过流风险。

Coordination Method of Arm Overcurrent Protection Settings in Flexible HVDC Transmission System

The malfunction of DC arm overcurrent protection may lead to the failure of AC fault ride-through. And the action rejection or slow action of DC arm overcurrent protection may lead to overcurrent of switching device during a DC fault. For the above problems, this paper discusses the configuration of arm overcurrent protection function of the converter valve in the valve control device and the DC protection device and the coordination of arm overcurrent protection settings in flexible HVDC transmission system. According to the coordination diagram for AC protection settings, the optimized cooperation method of arm overcurrent protection function in the valve control device and the DC protection device is proposed. Finally, a simulation platform is built in PSCAD/EMTDC. The simulation result shows that the proposed coordination method can achieve AC fault ride-through. At the same time, the proposed coordination method and protection setting method can reliably block converter and trigger the bypass thyristor under severe faults like short circuit between DC poles, thereby reduce the risk of overcurrent of power electronic devices.