Research on Line Selection of Single-Phase Grounding Fault in Neutral Ungrounded System Based on Phase Current Distortion

摘要

In order to solve the problems of single-phase-to-ground(SPG) fault line selection and technical complexity of existing distribution network neutral-point non-grounded system, the mathematical models of fault current under underdamped and over-damped conditions are established based on Karrenbauer phase-to-mode transformation and the boundary conditions of single-phase-to-ground fault. And combined with the steady-state modeling and analysis of SPG fault of the system, the difference of phase current distortion between fault line and sound line after SPG of the system is derived, and a steady-state line selection method based on phase current distortion is proposed. A large number of simulation experiments show that the method is simple to implement, and the results of line selection are not affected by factors such as the size of transition resistance, the location of fault points to buses, the length and number of lines.