多端线路电流差动保护实现故障定位及测距的新方法

Novel Method of Multi-Terminal Line Current Differential Protection for Fault Location and Location

多端线路具有多个T节点及分支的复杂性,已有的故障定位和测距方法不能直接应用到保护装置中。为此,提出通过故障类型选择故障定位和测距的序分量,以提高测距精度,即相间故障和三相故障时采用正序分量,而单相接地故障,多端线路所有节点的正序电压差小于预设阈值时采用零序分量,否则采用正序分量。为解决多端线路测距计算量大的问题,结合二分搜索法,通过评估T节点不同侧序分量电压的差异,实现多端线路的故障定位;将故障点两侧的电气量节点等效为双端系统,按选择的序分量进行双端故障测距。该方法经RTDS入网试验,可以满足现场要求,对比固定采用正序分量的测距方法,在高阻接地故障时具有明显的优势。

The multi-terminal line has the complexity of multiple T nodes and branches,and the existing fault location and distance measurement methods cannot be directly applied to the protection device.For this reason,it is proposed to select the sequence component of fault location and distance measurement by fault type to improve the accuracy of distance measurement,that is,positive sequence component is used for phase-to-phase fault and three-phase fault.For single-phase grounding fault,when the positive sequence voltage difference of all nodes of the multi terminal line is less than the preset threshold value,the zero sequence component is used,otherwise the positive sequence component is used.The electrical quantity nodes on both sides of the fault point are equivalent to a two-ended system,and the double-ended fault distance measurement is performed according to the selected sequential component.This method has been tested by RTDS network and can meet the requirements of the field.Compared with the fixed ranging method using positive sequence component,this method has obvious advantages in high-impedance ground faults.