Study On Su Qian Area 110kV Wu Xing Substation And 110kV Dong Gou Substation 20kV System Neutral Grounding Mode Selection And Operation

This thesis introduces the characteristics of the single-phase to earth short-circuit caused by arc suppression coil earthed neutral system and low impedance earthed neutral system of the 20 kV system.For 110 kV Wu Xing substation 20 kV adopts arc suppression coil earthed neutral system,the system can't correctly to select the fault line,and 110 kV Dong Gou substation 20 kV adopts arc suppression coil earthed neutral system,has caused one single-phase to earth short-circuit leaded to other line routes fault tripping off many times.through the research of equipment safety,insulation coordination,reliability,personal safety,grounding transformer selection,small resistance selection,relay protection transformation,etc.Use of PSCAD power system simulation software focus on the small resistance value choice,Suggestions to increase the low impedance earthed neutral system in two substations,the small resistance uses one of the two resistance values of 15 ohms and 20 ohms.This thesis suggests that the arc suppression coil of 110 kV Wu Xing substation should be put into operation normally,the small resistance does not put into operation.Suggestions the small resistance of 110 kV Dong Gou substation put into operation normally,the arc suppression coil does not put into operation.This thesis also proposes the Dong Gou substation and Yang Zhuang substation 20 kV system operation mode.This thesis proposes two substations flexible grounding operation,It basically solves the problem 20 kV arc suppression coil grounding system can't correctly select single phase grounding fault line and one single-phase to earth short-circuit leaded to other line routes fault tripping off.It has certain engineering application value.