Application Of Compressed Sensing In Fault Line Detection For Indirectly Grounding Power System

The small current grounding system with its good reliability of power supply is widely used in the low voltage distribution network in China. However, the single-phase grounding fault that takes place in the distribution network. This situation is frequent. Because the fault current is very small, fault line selection takes a long time and it is difficult to obtain accurate fault signal. So this is difficult to breakthrough the bottleneck of single-phase grounding fault line selection and takes a long time to find the corresponding effective solutions. So, how to make the fault lines selection process more accurately and quickly is very meaningful and important.This thesis mainly deals with this problem on the basis of the existing large research around to carry out the related research work. It aims to explore and improve the shortage of the existing fault line selection method. Firsly, What are the obvious features when system failure. This thesis made a detailed discussion and comb from two aspects of transient and steady. It summarized the characteristics of fault line and health line and their distinctions, which provides ample preparation and solid theoretical basis for future research and analysis. Then, this thesis has generally introduced the existing several kinds of traditional line selection method, analyzed their constraints, and summed up the existing obstacles and defects in these methods. Finally, through the above analysis and research, if you want to make the initial failure analysis more accurate, make line selection more quickly. Accurate fault signal of the original acquisition is very important. Many of the fault line selection methods based on the differences between characteristics of the transient information to judge, and traditional high-speed sampling may fold in the part of the high-frequency component. Make the signal appeared confused. So the success of the line selection based on access to more accurate zero-sequence current. But only reached the high-speed sampling frequency can make the fault signal to obtain more accurate. In this thesis, a new signal processing method of compressed sensing theory is studied and is applied in the line selection of small current grounding fault. Fundamentally solve the problem of sampling frequency limit, accurate fault signal, so as to improve the accuracy of fault line selection. Try to apply a new method of compressed sensing theory in this paper to achieve breakthroughs in the sampling frequency. Makes the fault line selection methods are no longer bound by the conditions, and then obtain accurate reconstructed signal. Beyond that also combine this theory and Hilbert-huang transform (HHT). Using matlab simulation, a lot of experimens of small current grounding fault for different types are carried out. they verify the correctness and reliability of this method and obtain the expected effect.