Regenerative Braking Energy and Power Quality Analysis in $2\times 25$ kV High-Speed Railway Lines Operating with 4QC Locomotives

The AC $2\times 25$ kV feeding system is considered as a wide applicated existing power supply system for high speed and high capacity railway lines all around the world. Multiconductor overhead catenary system (OCS), high-power four-quadrant converter (4QC) based trains and a large number of elements have made the power flow and power quality (PQ) analysis complex in such a system. In this paper, an accurate simulation of 4QCs along with traction motors and eight-conductor based OCS have been implemented for the 114 km double-track railway line with realistic information. The PQ analysis together with regenerative braking energy (RBE) assessment are carried out based on extracted voltage and currents waveforms. The proposed methodology is executed in MATLAB software taking into account train movement equations, speed profile and various modes of operation.