Study On Technique Of Failure Auto-isolation Of Branch Overhead Contact Line

Railway system belongs to first level load, any fault happened in this system will affect the stability and the security of the system. The short-circuit of overhead equipment of electrified railway is one of the most typical and direct fault. Once the fault of overhead equipment happened, the protect system of corresponding section would break electricity, even the tripping would happen in traction substation. That will affect the whole traction system. This character is especially apparent in the railway system with branch lines, it not only makes determining fault's type and eliminating fault hard, but also affect the whole system's normal run. Therefore determining fault's type and eliminating fault quickly is apparently important. The technique of failure auto-isolation of branches' overhead contact lines makes more sense to solve and study this problem.In this paper, first, the background and significance of this paper are introduced, and the research status of technique of failure isolation of overhead contact line is presented. The model of T-R-NF traction network is built by relative formulas, based on parameters of traction substation, overhead equipment, feed wires, rails and electrified locomotive. Some parameters of traction system are calculated based on original data.Second, the function of PSCAD/EMTDC is presented simply. Simulation model of T-R-NF traction network is built with PSCAD/EMTDC. It simulates different instance, such as normal run, short-circuit, and overload. Simulation of short-circuit includes mainline shorted, near end of branch line shorted, middle part of branch line shorted, end of branch line shorted and so on. Waves of voltage and current are obtained by simulation. The feasibility and necessity of application of failure auto-isolation technique of branches' overhead contact lines, which is based on wavelet theory, is described by combining the result of analysis and traditional determining method.Third, this thesis introduces the tools of MATLAB and the theory of wavelet transform(WT), and emphasizes biorthogonals. The data obtained from simulation of PSCAD/EMTDC is analyzed in MATLAB2007. Compact supported biorthogonal constructed by cardinal B-spline is used to obtain the instantaneous features, instead of traditional way which ignores lots of transient signals. By analyzing the instantaneous features, the threshold value as foundation of determining fault type is set.Last, the model of USB421 which is used to collect and transport data is presented. The collection and transportation of branch lines'data are realized. In this paper, the technique of failure isolation of branch lines based on WT and the device of failure isolation in railway system are combined. And finally, the interface of human-computer interaction is designed to realize data transportation and fault determination and ect.