Research On Fault Location For Distribution System Based On Wavelet Analysis

As the explosive development of power industry and scale expansion of electric distribution network, particularly, the construction of the smart grid,people ask more stable power supplying. Line protection has entered a new automation era of using computer protection.As a efficient tool for mathematical analysis, wavelet has been used in power system widely .In this Article, wavelet is used in radial distribution network and tree distribution network. Faultpoints have more complex transient waves,what are generated with a large number of harmonics. Particularly,because of the compensation coming from power system with neutral grounding via arc suppression Coil, the zero-sequence information amplitude of fault traveling wave become small and could be smaller then system normal working.So it is difficult to obtain the characteristics of traveling wave generated from a faultpoint. In this Article, catch the first traveling wave of fault transient information by type c traveling wave distance measuring method and wavelet analysis, determine the traveling wave speed of the zero-mode wave when system working normally and measure the fault distance exactly.For the tree distribution network,insert a voltage traveling wave into system and record the zero-mode voltage wave of reflected traveling wave when system working normally,while insert a voltage traveling wave into the fault phase and record the zero-mode voltage wave of reflected traveling wave when system working abnormally,then subtract the two waveforms and eliminate the first reflection wave of network nodes and calculate the fault distance by wavelet analysis. Based on the completion of ranging, measure and analysis the voltage to earth of fault phase which is at the end of every line,the line which has the smallest voltage amplitude or the fastest changeing voltage amplitude is the fault line.The method is that:measure the fault distance and determine the point which is like the fault point,then select the fault line. It can position the fault point on line , reduce the time of power failure and enhance the sustainability and stability of power supplying.In this Article, build simulation model of radial distribution network and tree distribution network in Matlab / simulink simulation system and use ideal power controled with a switch as voltage traveling wave signals what using in fault location.It gets a good positioning effect when simulating fault and location in line and branch nodes.The simulation result shows that the method based on type c traveling wave distance measuring method and wavelet analysis can accurately determine the fault location accurately.