Study On Fault Location Method For Single-Phase-to-Ground Fault Of Small Current Grounding System

In China, small current grounding style, including neutral insulated and neutral grounded with Petersen coil, is widely used in the distribution networks of 66KV or lower levels. Single-phase-grounding fault is the most common fault in the small current grounding system. How to locate the grounding point is a technical problem long existing.According to the characteristic of the zero-sequence current traveling wave appearing when single phase grounding fault occurs in small current grounding system, the problem that the error is too great when only the traveling waves of the same polarity are used is analyzed in the paper. Based on the analysis, a new method for fault location in small current grounding system is proposed in this paper, in which both positive traveling wave and negative traveling waves are used.Firstly, the author introduces the research background of fault location in small current grounding system in the paper, and analyzes all kinds of fault location methods existing nowadays. Secondly, the basic theory of wavelet transform and its application in the signal singularity identification are introduced, which supplies an advanced math tool for the traveling wave fault location method. Thirdly, the author explains the basic theory and main methods of traveling weave fault location, which provides a detailed theory basis for the new fault location method. Finally, the author demonstrates the principle and the detailed steps of the new method, shows the simulation results under all kinds of conditions, and analyzes the influences of all kinds of parameters. Based on the simulation, the correctness of the new method is proved.The new method has a good ability of anti-disturbing. Its reliability is also very high. Therefore, it is valuable for both theory and application.