Research Of Distribution Network Line Fault Detection And Localization Method

Distribution network fault will bring great harm to people's lives and social economy.Quickly and accurately to detect and locate the fault line of distribution network is a precondition to ensure the reliability of power supply.This has very important significance for the maintenance and safe operation of the system.Therefore,the paper takes the single-phase grounding fault of distribution network as the background,and researches on online detection,online location and isolation region offline location of distribution network fault.The characteristics of single-phase grounding fault of distribution network line are introduced.The current signal in the transient process of fault occurring to isolated neutral system and to arc suppression coil grounding system is discussed in this paper.Analysis to fault signal with wavelet transform is better accurate,so the paper uses this analysis method and selects appropriate wavelet and wavelet base to extract the information of a fault.Simulation results show that,the method can extract transient signal and weak signal of the fault reliably and detect fault signals more accurate and real-time.In this paper,the location of a fault line is based on transient signals in single-phase grounding fault of distribution network line.Using zero sequence transient energy polarity to make the matrix operations and combining with system topology structure for determining the location of the fault line,a location method of a fault line based on a transient energy polarity is presented.Simulation results show that,this method is not only suitable for low resistance fault,but also suitable for high impedance fault.The fault location in an isolation region of distribution network is determined and meanwhile,a specific fault point is located by means of signal injection.There are two method of injecting signal,namely,DC signal injection and S signal injection.By contrastive analysis,DC signal injection method is not affected by the distributed capacitance,inductance and grounding resistance.The method has high reliability for fault line positioning,but the process of positioning is cumbersome.S signal injection method has high accuracy for location of the fault,but it is easily affected by distributed capacitance and inductance of the line.Therefore,the paper combines the two methods into a DC-S integrated injection method,and the simulation results show that the novel method achieves the complementary advantages,and has high reliability and accuracy.