Research On Electric Railway Electromagnetic Influence On The Communication Line

ABSTRACT:With the development of electric railway, high-speed railway is developing rapidly, which has many characteristics, such as heavy traction load, large short-circuit current, high traffic density, strict reliability, and so on. The traction power supply system is a high-voltage, heavy-current, and unbalanced power supply system, which gives priority to the AT power supply mode and direct power supply mode with return line. Its powerful voltage and current of the traction power supply system will produce the strong electric field and magnetic field, which have dangerous influence and interference effects on transmission lines of weak current signal nearby.The main communication lines around the high-speed railway are the signal cables. The electromagnetic induction effect of the dangerous influence from traction power supply system of high-speed railway to the signal cables is closely related to the line maintenance personnel. The electromagnetic induction effect will directly affects the quality of communication, and threatens the personal safety. Therefore, the main research focus on the electromagnetic induction effect producing on the signal cables by the traction power supply system of high-speed railway.Taking Jinqin Passenger Transport Line as the research background, this paper researches the LEF on the railway signal cables resulted from electromagnetic induction effect detailedly. Through the current distribution of all parallel AT power supply system from running test, combining with the loop-analysis method, this paper gets the approximate expression of the current distribution. Then using the Carson formula to calculate the mutual impedance between the traction network conductors and the railway signal cable, the paper builds the hand-calculated model, and writes the program of the MATLAB calculation software, to get the changed LEF curve of core wire, corresponding to the different locomotive positions, when the locomotive current is always1000A.Then, the paper gets the LEF curve of core wire which is get by analyzing the data of the running test, when the locomotive current is always1000A, compares to the results of the calculation software writing by MATLAB and TRANAS software, and analyzes the sources of error.In addition, this paper also analyzes the effects on LEF induced by different ways of cable grounding, up-line driving, and down-line driving, and the relation between current and the LEF. And the paper gets the conclusion through the short circuit test in parallel AT power supply mode, that the traction network T-R short circuit has the greatest effect on the LEF of core wire, and calculates the maximum LEF in the condition of T-R short circuit. According to the variables in computing, this paper come up with the corresponding measures for decreasing the induced voltage in the conclusion part.