Моделювання розповсюдження гармонійних завад від електрорухомого складу у несиметричній рейковій лінії

Abstract

The investigation of the traction current harmonic distribution in rails from electrical rolling stock and their influence on the operation of track circuit's equipment is an important component of the general problem of ensuring electromagnetic compatibility of traction power supply system with signalling and communication lines at a railway transport. This problem retains its relevance at present due to the wide introduction of new types of rolling stock with pulsed converters of electrical energy, as well as with an increase in the speed of trains. Simulation of the propagation of harmonic interference in the traction network, along with measurements of their values during acceptance tests of electric rolling stock and in its further operation, is necessary for analyzing and determining the causes of the occurrence of excessive interference in track circuits and making decisions to eliminate their harmful effects on signalling systems. The models proposed in the literature are concerned mainly to the distribution of the traction current or its harmonic components in the rails, while the functional safety of track circuits is primarily affected by the difference current in the rails. Analytical solutions proposed in the literature for equations that describes voltages and currents in asymmetric rail line were obtained under certain assumptions and are cumbersome, that complicates their practical application. The aim of the work is to develop a model for traction current harmonic distribution in asymmetric rail line from electric rolling stock that using simplified expressions for the current in the rails, which is possible with minor rail line asymmetry , and simulation based on the developed model the effects of longitudinal and transverse asymmetry of the rail line on the distribution of the difference harmonic interference currents in rails. To test the developed model, the asymmetry coefficient of the traction current harmonic with a frequency of 25 Hz along the rails have been simulated. As a result , it was shown that the current asymmetry coefficient increases with increasing longitudinal and transverse asymmetries of the rail line and with distance from the electric train. The observed increase in the asymmetry coefficient is partly due to the decrease in the total harmonic noise in the two rails with distance from train. As the distance to the train increases, the differential noise current also increases. With a simultaneous excess of the impedance and conductivity of the ballast of one rail compared to another rail, the asymmetry coefficient in some cases can significantly exceed the normative values.