Research On Single Phase Grounding Fault Location Of Small Current Grounding System Based On EEMD

In China’s medium and low voltage distribution network,the grounding mode is mainly small current grounding,including neutral grounding through arc suppression coil and neutral ungrounded.The reason for using a separate network is that the error of one person is more than 75%at this time,because the line will not produce a corner,and then move the current line later.At this time,the system will continue to operate with fault.However,if the fault can not be eliminated in time,the fault will expand and damage the relay protection device of power grid for a long time,Affect and destroy the stable operation of the system.Therefore,it is of great significance to study the single-phase grounding fault location of small current system.Firstly,this paper introduces the single-phase grounding fault location methods of small current systems at home and abroad,and summarizes their advantages and disadvantages.By analyzing the transient and steady-state characteristics of fault,it is concluded that the transient characteristic quantity contains a large amount of fault characteristic information,and the amplitude of transient characteristic quantity is several times of the steady-state characteristic quantity,which provides a theoretical basis for the next fault location.In order to solve the problem of inaccurate results caused by the difficulty of extracting transient features,the Ensemble Empirical Mode Decomposition(EEMD)algorithm is used to extract fault features,which can well suppress the mode aliasing phenomenon in the decomposition signal of Empirical Mode Decomposition(EMD),Then the modal inherent energy and energy weight factor of the signal are defined and combined with them,and the maximum energy weight factor is proposed as the line selection criterion;Because the line structure of distribution network is complex and there are many discontinuous points of wave impedance,the refraction and reflection of traveling wave are complex,and the wave head of traveling wave is difficult to identify.Therefore,this paper combines EEMD and Teager energy operator to extract the wave head information.Firstly,the signal is decomposed into multiple single component signals by EEMD,and then the single component signal is modulated by Teo which can reflect the instantaneous transformation of the signal to obtain the energy spectrum.From the energy spectrum,the time difference between the initial traveling wave head and the measuring end at both ends is calculated,and the fault distance is calculated by substituting the two terminal traveling wave method.Finally,the simulation results show that the location method is less affected by fault factors,can locate accurately,and is more accurate and adaptive than EMD-TEO.Figure[45]Table[7]Reference[70]...