| The construction of high-speed railway network is becoming more and more important in the national economy.Connection of phase change is generally used in existing traction substation of traction power supply system for reduce the three-phase imbalance.But this kind of connection has the neutral section problem.EMU or locomotive of high-speed railway adopt high-power A.D.A.traction driving system,which also aggravate the negative sequence problem.Continuous cophase traction power supply system can primely solve the negative sequence problem of grid and the neutral section problem of traction network.The existing traction network primarily adopts the protection based on the industrial frequency electric quantity.Travelling wave protection has obtained considerable development in UHV and HVDC transmission line protection.In this paper,a model of Continuous Cophase Traction Power Supply System adopted AT-powered based on A.D.A.converter is built,characteristics of travelling wave propagation in traction network are analysed,the principle of transient current polarity comparison based on ESMD and wavelet modulus maxima of traction network is put forward,the protection principle is verified by simulation analysis of traction network fault.The model of continuous cophase at traction power supply system is bulit,which includes traction network model according to the line paramaters of exisiting AT traction power suppply system,traction substation model of three-phase to single-phase based on A.D.A converter,CHR2 A.D.A locomotive model.The applicability of this modle is demonstrated by simulation.Traction network lines,which is unblanced lines,cann’t directly adopt the matrix of phasic decompositions that aim at the blance lines.The matrix of phasic decomposition applied to this unbalanced lines and characteristics of travelling wave propagation in traction network are studied.Calculating traction network parameters using Carson theory,the phase-mode transformation matrix for the unbalanced line is solved by using the obtained parameters and the wave equation.The appropriate mode is chosen as the traveling wave analysis object through comparing each modes by velocity and Ensemble Empirical Mode Decomposition.Analyze the propagation characteristics of voltage and current traveling wave in traction network,and the influence of autotransformer and traction substation on traveling wave signal in traction network.Study on traveling wave protection criterion of traction network in traction power supply system.This paper introduces the principle of traveling wave protection of current polarity,wavelet modulus maxima and Extreme-point Symmetry Modal Decomposition method.The principle of transient current polarity comparison based on ESMD and wavelet modulus maxima of the continuous cophase traction network is proposed.Analyze the effect of the fault location,the transition resistance and the initial angle of the fault on the protection method.Simulation of fault and disposaing falut signal by PSCAD/EMTDC that is electromagnetic transient simulation software and MATLAB verify the protection principle and its influnencing factors. |
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