Single Phase Grounding Fault Location Method Based On SVM For Small Current Neutral Grounding System

The neutral indirectly grounded way is mostly adopted in distribution systems of6~66KV in china, and they are belong to small current neutral grounding systems. The single phase grounding fault of small current neutral grounding system is very common in power network. Because the fault current is too weak to be captured, and there are lots of branches on the lines, the fault location method of transmission line is inefficient for small current neutral grounding systems. In order to find the fault point quickly, a comprehensive method which combined C-type of traveling wave and support vector machine is proposed.The current signal is considered as the analysis signal. The first step of the method is using C-traveling wave fault location method to measure the fault distance and then to find the fault section by using support vector machine. Connecting with the practical situation that the captured signal contains a lot of noise, the noise-reduction methods are studied in this paper in order to increase the fault location accuracy. By using the advantage of wavelet and empirical mode decomposition, the reflection wave signal can be processed effectively. Be different with the traditional C-traveling wave fault location method, the fault distance is determined by finding the first breakpoint of the waveform by subtracting the reflection wave signals from the fault line and the normal one.After the distance of fault location is determined, the support vector machine is used to find the fault section through the learning and training of different characteristics of reflection waves in different fault sections. The theory analysis and simulation results show that:the comprehensive method can determine the single phase grounding fault point in small current neutral grounding systems accurately.