Study On Fault Line Selection For Single Phase-To-Earth Fault Of Very Long Power Supply Line In Qingzang Railway

Non-ground neutral system and arc-suppression-coil-ground neutral system are called non-direct ground neutral system that is widely used in power distribution system. The study of the fault line selection is one of the main fields when non-direct ground neural system is used. The QingZang railway is across the QingZang altiplano. Because of short of power sources in the altiplano, very long feed line of power distribution system have to be used when one of the substations is failed to operate, in order to guarantee the reliability and security of the power supply. So the fault line selection for very long feed line deserves to be studied.The fault transient and steady characteristics of single-to-earth fault for non-direct ground neutral system are analyzed in detail. This paper gives a general overview of various neutral grounding modes. Some existing theories schemes on the fault line selection have been summarized systematically. Then, some problems, which should be solved, are proposed.Secondly, the simulation model of very long feed line of power distribution system of QingZang railway is set up. A novel algorithm based on the increment of the phase current difference for fault line selection is put forward. And setting rule of these principles is discussed in the paper. A variety of simulation results show that the proposed method is accurate and reliable.Finally, because single fault line selection method using only some parts of fault information has poor reliability, the paper uses information fusion, fuzzy set theory to integrate all fault line selection method to amend the arithmetic.