Fault Signal Simulation And Feature Analysis In Neutral Un-effectual Grounding Power Systems

In China, most of distribution network uses Neutral Un-effectual Grounding Power Systems, single-phase ground fault system accounts for a large percentage of the total fault, and arc ground fault occurs frequently. At present, when researcher set up the single-phase ground fault model arc, they usually consider arc resistance as resistance of zero(metallic ground) or fixed value resistor. Because the simplified fault model can't accurately reflect the actual situation, it impacts the study of fault detection methods in neutral un-effectual grounding power system fault. Therefore, establishing an accurate model has an important significance. It can guide fault line selection.Depending on the different fault types in neutral un-effectual grounding power system, in this paper, it studied state characteristic and transient characteristic of failure system. Furthermore, it not only established a more accurate arc model but also did lots of simulation. Using MATLAB simulation software to simulate single-phase fault in the neutral un-effectual grounding power system. And analyzed the different conditions which can effect on system failure characteristics.After simulation, using the scientific calculation method to extract fault signal. In this paper, it selected FFT to extract the steady-state characteristics. And it proposed a method of multi-resolution combining with wavelet packet transform to extract transient fault feature. According to the characteristics of different fault, this method can select the fit decomposition scale and band. Making more prominent fault signal characteristics, which will help researchers at the fault line selection.