高压换流站交流滤波器最后开关跳闸后，将启动本大组交流滤波器联线差动保护跳闸回路。以±800 kV云南—广东特高压直流工程为背景，分析了间隔控制单元6MD664中大组滤波器最后开关的软件逻辑以及相关的硬件回路，指出了其中存在的设计缺陷，提出了修改软件逻辑、硬件回路改进措施。

In HVDC converter station,the connection differential protection will be activated because of a trip of the last circuit breaker in AC Filter.In this paper,taking the UHVDC transmission project of Yunnan-Guangdong as an example,the software logic and related hardware circuit are analyzed of the last circuit breaker in AC Filter of the 6MD664 interval control unit,where the design defects and improvement are presented.