Twelve sequence components method based on matrix change decouples the mutual effect of four transmission lines on the same tower well. Among all the components, E component current travels on all the four lines while F, G, H currents travel only on two of the four lines, which are referred to as loop flow component. This paper found that the F, G and H component currents of non-faulted phase have value of zero and the faulted phase have a nonzero value when a fault happens on a single line of the four transmission lines; when the fault occurs on different lines, there is a fixed-phase relationship among twelve sequence components. Therefore, this paper proposes a new method of selecting the faulted line and faulted phase and constructs corresponding phase selector. By simulation of four transmission lines' EMTP models built on both symmetrical and unsymmetrical data, the proposed method is proved to be correct.%同杆四回线的12序分量法将四回线上的相电压、电流分解为E,F,G,H四种分量,解决了四回线的互感问题.其中F,G,H分量只在四回线路内部的两回线间流过,称为环流分量.在四回线发生单回线故障时,存在非故障相的环流分量电流为零,故障相的环流分量电流不为零的特征,而当故障发生在不同回线路上时,12序分量之间存在不同的固定相位关系.基于上述两点,提出了一种四回线发生单回线故障时故障相的识别方法,并构造了相应的选相元件.采用实际数据用EMTP建模,并进行大量的仿真实验,结果验证了此选相方法的正确性.
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