Method and device for detecting directional grounding fault based on three phase current variation

摘要

A method for determining a fault phase during a single phase grounding fault and determining whether the fault is a downstream fault or a upstream fault. The present invention provides A directional grounding fault detecting method, comprising: a. detecting a grounding fault based on sampled three phase currents i_A, i_B and i_C, and obtaining a time point t corresponding to an moment at which the grounding fault is just detected; b. determining whether it is a single phase grounding fault or a two phase grounding fault based on three incremental phase currents Δi_A, Δi_B and Δi_C at moment t; and c. when it is determined as a single phase grounding fault, it is determined whether the fault is an upstream fault or a downstream fault based on an amplitude of the incremental phase current of the faulted phase.