A new method for fault line selection based on wavelet de-noising and transient current energy grouping comparison in ineffective grounding system

This paper analyses the development of the fault line selection and the advantages of using transient current for fault line selection,then proposes a new fault line selection method based on wavelet soft-threshold de-noising and transient current energy grouping comparison in arc suppression coil grounded system.It eliminates the noise in the current firstly,and then sorts the denoised signal,and makes the normalized energy of each two zero sequence currents.Through comparing the normalized energy with a given threshold,the accumulation variable value(AVV)of each outlet can be gained.The fault line will be selected by comparing these AVVs.This method has the advantages of simple principle,reliability, low computational complexity, and strong anti-interference ability. It immunes from the influences of compensation degree,fault location,phase angle,load, and fault transient resistance.The simulation results verify the effectiveness of proposed method.