Study On Fault Location Of Bilateral Cross-coupling AT Power Supply Traction Network

Unilateral cross-coupling AT power supply mode is widely used in high-speed railway in China.With the continuous development of the construction and the increasing speeds of Chinese high-speed railway,higher requirements for the power supply capacity and reliability of traction power supply system are put forward.The combination between bilateral power supply technology and AT traction power supply technology can improve the quality of power supply and the supply capacity.Therefore,bilateral traction power supply mode has important practical application value.Traction network is an important part of traction power supply system and a power supply network with high incidence of faults.A lot of manpower and material resources can be saved by the precise location of the fault points after they have occurred.When the traction network adopts bilateral power supply mode,compared with the unilateral traction network,the topology of the traction network changes,which leads to the change of voltage and current distribution in the traction network in case of short-circuit fault.Therefore,it is necessary to study the adaptability of the existing traction network fault location principle in the bilateral power supply system,and put forward the fault location strategy based on the characteristics of the bilateral cross-coupling AT power supply mode,which is of great value to improve the safety and reliability of the bilateral power supply traction network.In this paper,according to the different connection modes of sectioning post,the bilateral cross-coupling AT power supply traction network is divided into two different types:the bus connection mode and the disconnector connection mode.For the traction network under the two connection modes,the characteristics of voltage,current and impedance in the traction network when T-R and T-F faults occur in the traction substation-AT section and AT-sectioning post section are calculated.The expressions of AT neutral current ratio,cross-line current ratio,up-down-line current ratio and short-circuit impedance are obtained.The adaptability of the traditional fault location method under the bilateral cross-coupling AT power supply mode is analyzed,and the identification method of fault section,line and type is given.A simulation model based on Matlab/Simulink is established to verify the validity above conclusions.Finally,according to the characteristics of bilateral cross-coupling AT power supply mode,a fault location strategy for bilateral power supply traction network is proposed.