Distribution Network Based On Morphology - Stationary Wavelet Packet - Hilbert Transform

Electricity energy has become one of the most important, the stability of power supply system has become very important, this is not only related to people’s daily life, but also related to the development of the world. For the timely elimination of security and stability of the power supply fault is fundamental. The small current grounding system is mainly used in China in single-phase grounding the chance of failure, the single-phase grounding fault is the most common fault in distribution system of resonant grounding, when single-phase grounding fault will bring great inconvenience to users in the network. Due to various factors and uncertainty of the fault line selection is difficult. Therefore, research on small current grounding the single-phase fault line selection has become a hot and difficult problem, also pay attention to it for the combination of mathematical theory analysis of the idea of fault information. The steady-state amount of line selection method in industry Line line line process in fact is not practical, grounding fault transient current than the steady state current, based on transient component of fault line selection method of high precision, the effect is good and is not affected by the arc suppression coil. However, due to the current system of structure and operation condition is not the same, and cause the system single phase earth fault, transient signal is not obvious or not stable, if only using a single characteristic component selection method could not completely solve the small current grounding system fault line selection problem, but also impossible to achieve 100% correct line selection. So, we must through the selection method of organic synthesis, to establish a perfect fault line selection scheme.Based on the analysis of the small current grounding line selection algorithm based on a mathematical morphology algorithm integrated line selection based on the algorithm, using the two structural elements of parallel filtering to preprocess line selection data composite filter, and then analyze the fault characteristics of transient zero sequence current, calculate the instantaneous frequency by Hilbert transform, wavelet decomposition to extract feature band calculation of band energy ratio factor, according to the calculated band than the factor of ground current components for high frequency components accounted for the main component, using the principle of maximum fault line transient energy fault line; for low frequency components which are the main components, the DC component method for DC strong zero sequence current of fault line and the non fault line, almost no DC component, so can according to the difference. Row select line. The comprehensive method for fault line selection can be adaptively selected wavelet decomposition of signal feature extraction, reduce time of the algorithm, for the actual creation of conditions. At the end of this paper, through Simulink power system simulation software to establish small current grounding system model and the obtained fault zero sequence current signals by Matlab software for processing. The final validation results show that the proposed fault line selection method in a certain extent, improve the accuracy of fault line selection, anti-jamming and real-time.