A Method of Small Current Grounding Fault Diagnosis Based on Catastrophe Value

Abstract

The distribution network usually adopts the operation mode of ungrounded neutral point or grounded through arc suppression coil to improve the stability of the system, but under these two working modes, the output current signal of the system is weak when a single-phase grounding fault occurs, which leads to the difficulty of fault diagnosis. In order to realize the diagnosis of small current grounding fault under these two working modes and improve the accuracy of small current grounding fault diagnosis technology in distribution automation (DA) system, through the analysis of the transient characteristics of the system when grounding fault occurs, combined with the relationship between the transient zero sequence current of fault line and non-fault line and the relationship between transient zero sequence voltage and zero sequence current when grounding fault occurs, Based on the sudden change value of zero sequence voltage and zero sequence current, a small current grounding fault identification method is presented. MATLAB is used to simulate the small current grounding system model of distribution network with ungrounded neutral and grounded through arc suppression coil, and the simulation results are analyzed to verify the accuracy of the proposed discrimination method.