Study Of Fault Line Selection And Fault Location For Single-phase Earth Fault In The Small Current Grounding System

In the process of the development of modern power system, the reliability and safety of the system are also improved, but the fault of power system is inevitable. Because the small current grounding system is widely used in the distribution network, the fault location of the single-phase grounding fault system is always the hot research of power system.Firstly, the fault characteristics of the single-phase grounding system for small current grounding system are divided into two parts: steady state and transient state, the results show that the steady state analysis should be carried out from different cut point and the results of fault location are not ideal when the neutral point is not the same. However, from the other hand, transient analysis requires only one standard, that is, the transient process is not affected by the neutral point of the ground. In the transient process of contains a lot as a selected line and ranging based on the high frequency characteristics of information, in order to extract the feature information, we use wavelet transform to decompose the fault signal to different frequency band and to analyze the transient information, can select the fault line and measure the fault distance.Secondly, due to considering the measured in the actual line of fault transient signal feature is the presence of noise, in order to get more accurate fault line selection criterion proposed by using the multi-objective particle swarm algorithm to optimize the matching pursuits algorithm de-noising, and implemented on the basis of the signal and the fault signal de-noising.Once more, this paper puts forward the neutral point through optimization of the system arc suppression coil grounding, improve the shunt resistance method for fault line selection problem, not only reduces the voltage across the resistor under, but also eliminate the security risks of the system. According to the fault line selection criterion, the transient component of the zero sequence current of each line is collected, and the wavelet transform is used to verify the details of each line, judge the fault line.Finally, after research and analysis of the basic theory of traveling wave fault location and the original wavelet transform modulus maxima verify fault location method, obtained ranging error of this method is relatively large. Proposed a method which is based on wavelet and improved singular value difference spectrum the traveling wave ranging, through the simulation results to measure the fault distance, less error than modulus maxima method, range relatively high accuracy.After a lot of simulation experiments verified the validity and accuracy of this paper’s methods, which are the fault line selection and the fault location.