\(\Delta \)-Y Transformer-based Railway Co-phase Power System

In a railway traction substation, power electronics devices are used in conjunction with a special transformer of a traction substation to mitigate power quality issues. To study the use of power electronics devices with conventional transformer, this research studies the use of a conventional Delta-star transformer along with power electronics converters. The system forms a co-phase system using single-phase back-to-back converters, which addresses the issue of current unbalance and power factor correction. The control theory derives the value of currents to be drawn from the secondary of traction transformer so as to draw balanced power from the three phases of the grid supply. Accordingly, a control algorithm is developed which calculates the reference converter currents and operates the converters. Validation of control theory is done analytically. Simulation and real-time hardware-in-loop experimentation are performed under different loading conditions. The steady-state and dynamic behavior of the system is studied to validate the proposed control algorithm. The work is presented as a proof of concept.