YD型换流变三角形绕组CT饱和对直流保护的影响及对策  

Impact of the CT saturation of the delta winding on the HVDC protection and its countermeasure

作　　者：张侃君[1] 戚宣威[2] 胡伟[1] 张时耘 陈堃[1] 尹项根[3,4] 

机构地区：[1]国网湖北省电力公司电力科学研究院,湖北武汉430077 [2]国网浙江省电力公司电力科学研究院,浙江杭州310000 [3]强电磁工程与新技术国家重点实验室(华中科技大学),湖北武汉430074 [4]电力安全与高效湖北省重点实验室(华中科技大学),湖北武汉430074

出　　处：《电力系统保护与控制》2016年第20期99-105,共7页Power System Protection and Control

基　　金：湖北省电力公司科技项目(鄂电科研(2014)第110号)

摘　　要：为提高直流换流器桥差保护的可靠性,防止其在交流系统发生短路故障、励磁涌流等扰动期间误动,提出了一种换流器桥差保护应对CT饱和的方法。理论分析与数字仿真表明,YD换流变阀侧三角形绕组在交流扰动期间流过零序环流将导致桥差保护出现虚假动作电流,引发保护误动作。对此问题,提出了通过引入三角形绕组零序环流作为制动量的桥差保护防误动策略,并利用零序环流与桥差电流出现的相对时间差,判断是否投入该防误动策略。仿真表明,该方法能够在提高桥差保护在交流系统扰动期间可靠性的同时,不影响桥差保护对于内部故障的灵敏度与动作速度。In order to improve the reliability of the bridge differential protection for the DC converter, prevent the misoperation of the protection during short-circuit fault and the inrush current, the countermeasure for the CT saturation of the YD converter transformer of the bridge differential protection is proposed. The theoretical analysis and the simulation test disclose that the CT saturation in the delta winding of the YD converter transformer during the disturbance of the AC system will cause the false operation current, resulting in the misoperation. To solve this problem, the paper proposes a countermeasure that introducing the zero-sequence circulating current as the restraint current of the bridge differential protection. The time difference between the increase of the zero-sequence circulating current and the rise of the bridge differential current is utilized to determine whether to apply the proposed countermeasure. The simulation tests indicate that this countermeasure can improve the reliability of the bridge differential protection during the disturbance in the AC system, and meanwhile would not affect the sensitivity and the speed of the bridge differential protection for the internal fault.

关 键 词：直流输电 电流互感器 暂态饱和 桥差保护 励磁涌流 

分 类 号：TM721.1[电气工程—电力系统及自动化]