Research On Traveling Wave Protection Of Traction Network Of Through-type Cophase Traction Direct Power Supply System Based On VMD

With the rapid development of Chinese railway transportation,high speed railway has become adazzling business card in our country.Now the traction power supply syetem using different phase power suppil mode,that cause some problems such as the public power grid three-phase unbalanced load,negative sequence,harmonics or other power quality problems.At the same time,the locomotive passing neutral section insulator of contact line is also a problem.These problem have seriously affected the development of railway transportation.In order to solve these above-mentioned problems,many experts and scholars have made correlation studies,and put forward continuous cophase traction power supply system,that will solve these problem largely.The existing traction power supply system is mainly protected by distance frequency,whice is part of power frequency protection.It will influended greatly by transient resistance of the fault point and other factors.But action of the traveling-wave protection is faster,and it will not affected by the transient resistance of the fault point,transformer saturation,system oscillation or other factors.Alarge number of research results have been achiened in the traveling-wave protection of HVDC and AC transmission lines.So research on traveling-wave protection of continuous cophase traction power supply system have important sense.In this paper,I bulid a PSCAD simulation model of continuous cophase traction direct power supply system.According to the line structure and parameters of an actual traction network,work out the Phase-Mode Transformation Matrix which is applicable to unbalanced line of the system.I also analysed the tracelling wave influenced by same phase traction substation and electric locomotive in this model,and studied the propagation chararacteristics of tracelling wave on continuous cophase traction direct power supply system traction net.In this paper,I introduced Varitinal Mode Decomposition(VMD)and Wavelet modulus maxima theory,and combines them with traveling-wave protection,put forward traveling wave discriminant direction protection of continuous cophase traction direct power supply system traction network based on VMD and Wavelet modulus maxima,traveling wave current directional protection of continuous cophase traction direct power supply system traction network based on VMD and Wavelet modulus maxima.the simulation analysis of PSCAD and MATLAB software have proved the feasibility of these two protection method.This paper also analyses influence of different fault location,falut transition resistance and fault inception angle,It have proved that these two protection method have high reliability.