Determination of Electromagnetic Noise from a Power Supply Substation of Railway Traction Systems

This paper deals with 2 methods for the evalution of the electromagnetic noise that occurs when supplying electric trains from substations. The waveforms corresponding to the supply voltage from the substation and the current absorbed through the supply line by electric trains in different operational contexts are analyzed. Aspects of electromagnetic interference and electromagnetic noise in railway traction systems are discussed. Specialized standards that address the electromagnetic noise and effects produced by the electromagnetic interference in the railway electrical network are briefly presented. Two methods were used for the evaluation of the electromagnetic noise: the method of mean signal and the method relying on the decomposition/recomposition of individual periods using Wavelet Packets. 7 real datasets of 50 consecutive periods are analyzed with both methods, computing signal to noise ratios and other quantities (extreme and mean values and percentage relative differences between results provided by different methods). Conclusions are drawn considering the analysis results.