Analysis And Improvement Of Line Selection Device Based On Small Current Grounding

At present,the distribution network in our country mostly adopts the small current grounding mode,mainly including the neutral point ungrounded and the neutral point grounded through the arc suppression coil.This kind of grounding method can better improve the reliability of power supply,so that in case of single-phase grounding fault,the system can still maintain three-phase symmetry,and the distribution network can still operate stably for 1-2 hours.But at the same time,because of the small fault current,it is not conducive to the fault line selection.At present,there are many disadvantages in the methods of route selection,such as inaccurate route selection and too long time for judgment.However,with the development of distribution network becoming more and more complex and the increasing load,the long-term operation of power grid with ground fault.On the one hand,it will cause system over-voltage,impression of equipment safety,on the other hand,it is easy to cause fault expansion,leading to more serious grid accidents.Therefore,in view of this situation,it is of great significance to study and improve the method of line selection for small current grounding fault.This paper first describes the significance of small current grounding line selection and the research status at home and abroad,and makes a simple description and comparison of the existing line selection methods.Secondly,the small current grounding system with different grounding modes is analyzed and compared,and the fault analysis of steady-state and transient characteristics is carried out respectively when single-phase grounding occurs.Then it compares the advantages and disadvantages of several existing methods of line selection in Hefei area,and explains in detail the latest methods of active intervention security line selection.At the end of this paper,taking the Yin Xing road transformer in operation as an example,the primary wiring of the devices in the station,the functions of various components,the operation logic of the device,and the operation effect of the device are described one by one.It is proved that the method of active interference security line selection is accurate and effective,and it successfully solves the problems of line selection difficulty and long judgment time existing in the current small current grounding system,which has practical and reliable operation value..