Research On Step Voltage Of Medium-voltage Distribution Network Grounding Fault

With the increasing scale of the grid,the medium voltage distribution network after grounding short circuit failure,will cause three-phase system imbalance,short-circuit point may be a large short-circuit current,short-circuit current in the formation of the step voltage Has been widely valued.This paper has a certain engineering significance and practical value for the step voltage problem of medium voltage distribution network grounding fault.This paper introduces the development situation and the advantages and disadvantages of different grounding modes of the 10 kV distribution network,and analyzes the structure and working principle of ground transformer in the distribution network.For distribution network neutral point grounding,neutral point via arc suppression coil earthing and neutral point via small resistance grounding three way when earthing fault occurring fault current of theoretical calculation and using Matlab software to the simulation of fault current,it is concluded that accords with the theory of the simulation waveforms and data.In this paper,the theoretical calculation formula of the step voltage generated by the uneven soil model is put forward.The fault type of analysis of the medium voltage distribution network overhead line grounding fault types,the direct ground wire,conductor approved by the branches of single-phase grounding,pole the cross arm of step fault cases of using finite element software simulation,analyzing the influence factors,and the neutral point via small resistance grounding mode failure occurs the problem of large step reducing measures are put forward.Also on neutral point via small resistance grounding mode of the underground cable laying this paper analyzes the causes of ground fault occurs,and the step voltage produced by fault current are simulated,it is concluded that the main influence factors,and put forward the measures and reduce the step voltage.