Transient Analysis Of Track Circuit In The Adjusting State

Analysis and calculation of track circuit is an important issue of railway transportation security. At present, the research on track circuit are mostly concentrated on spatial domain according to the researches status of track circuit analysis in internal and overseas. However,when the track circuit is operating in relatively adverse transport environment, it is extremely difficult to confirm the actual working states in spatial domain. Therefore, from the perspective of the possibility of transient process, it is necessary to consider the analysis of track circuit in time domain. In this thesis, the time domain numerical solution method is researched to analyze transient process of track circuit in the adjusting state by aid of transmission theory, differential equation numerical solution theory, etc.The adjusting state, as a safe working state of track circuit, whose analysis is the basis of the analysis of track circuit. From the perspective of the differential calculus, firstly, the whole track circuit is divided into finite segments and these segments are equivalent to lumped parameter circuits, then the transient analysis and mathematical calculation model of track circuit in the adjustment state is established according to its characteristics combined with uniform transmission line theory. This model can obtain detailed and accurate calculation while the process is also simple and easy to achieve. Then, through this model,transmission line equation in the adjusting state is deduced. The solution of transmission line equation is the core of transient analysis of track circuit.Track circuit is considered as uniform distribution parameter circuit. According to the analysis of transmission line transient process in internal and overseas, through the reference of numerical solution method of transmission line, finite difference time domain(FDTD)method and alternating direction implicit(ADI) FDTD method are chosen to obtain the solutions of track circuit transmission line equations. Refering to the Lax equivalent differential formation, the partial differential equations group is dispersed in time spatial domain based on the theory of partial differential equation and the time domain solutions are got. At the same time, the error and stability analysis researches for the properties of track circuit differential formations are also needed according to the requirements of the algorithms themselves.Finally, according to lumped parameter equivalent circuit of track circuit at the sending end and receiving end, the boundary conditions in different load cases are confirmed.Transient responses of track circuit in receiving end are simulated by Matlab corresponding to different electrical parameters(rail impedance, ballast resistance) and different signals in sending end. The results show that the time domain solutions of FDTD method are conformed to the general transmission characteristics of track circuit, and compared with the simulationcurves of ADI-FDTD method, their simulation results are consistent, which further verify the correctness of the results in this thesis.