Reduced Rating Railway Power Conditioners in Co-phase Traction and Traditional traction system

This paper aims at reducing the rating of the power conditioners used in Railways. Co-phase traction employs a Railway Power Conditioner (RPC) for active power balancing, reactive power compensation and Harmonic elimination. The relation between the RPC Rating and the magnitude of the compensating currents and the power angles of the line currents is deduced. Different cases are considered with different combinations of the phase angles, and the best possible case is selected using theoretical analysis and verified by simulation using PSCAD. Comparison is made between the compensated and uncompensated case. The effect of an additional capacitance on the dc-link voltage is also studied. This RPC system is employed in a Traditional traction system used in Indian Railways, with neutral sections and the resulting changes and THD levels of the grid side currents are observed. These results are compared with the Co-phase Traction with RPC and the change in THD levels is noted.